No Fertility In Eggs

Hi everyone, I have three roosters. One is three years old and the other two are about 22 months old. I have a flock of fifteen hens who range from 15 months to 30 months. They are all in their prime. All the hens are laying regularly, and the roosters are seen mounting on them regularly. However, I just got an incubator and started candling the eggs and they are zero for twenty so far. Twenty eggs, zero fertilization. These roosters are active. If you watch them for ten minutes, they are getting up on the hens, and they seem to be spreading the love pretty liberally, not just one or two favorite hens. The hens are Rhode Islands and sex links.

I have not lost a bird, ever. They get fresh water and plenty to eat everyday with scraps and other specials, and all seem totally healthy, with no interruptions in laying or any other sign of trouble.

The older rooster is a bantam and he is about three years old while the other two are 22 months. They respect him and he is the clear leader of the flock, despite being tiny. The other two are Rhode Island Reds, and they are at least three times bigger than him. They mount the hens constantly, and he never does, but he is the only one who crows. The big ones do all the mating but never crow, and they are passive around him and back away when he is nearby. I have never seen any of these roosters fighting. They are not aggressive against me, nor one another, ever. Are they all low T? What's up?

I am wondering if it is possible that the little bantam's presence there is discouraging them from actually doing the deed. They are clearly mounting up, but maybe not actually penetrating? Is that a thing? Is their respect for his leadership keeping them back? Is that a thing?

Today I removed the little bantam to see how the flock dynamics change, and I plan to keep candling all the eggs to see if I get any fertile.

Has anyone ever encountered this kind of problem?

Chickens are easy and very hard to understand. It doesn't sound like any of your roosters are "low T", but I am going to walk through their behavior with you and we can see if the problem might be something we can talk out.

The Head Rooster is going to be the rooster that crows first, when there's any sort of reason to crow - that sounds like your bantam roo. The other roosters will crow in the order they fall within the pecking order of your flock. Since the other two roosters aren't crowing I'm going to posit that they might have some sort of issue. That's a thing to be put aside for now.

In the flock, the hens will try to lay in an established nest. The RIRs will be more likely to go broody, which is one thing that Permies like (within reason), but I have had sex links go broody, too. A hen going broody this time of year, in the Northern Hemisphere,  is considered a sign of a good broody hen, wanting to start a family. None of your hens have that particular mindset. That's fine.

Chicken mating is a case of, effectively, putting two tubes of toothpaste opening to opening and then squeezing one of them, trying to make the toothpaste go in the other tube. A hen that, for whatever reason, doesn't like that rooster, has some (ineffective) ways of stopping things at that point, but chickens can usually make it all work the way evolution has set it up - chickens don't have any of the fancy bits that some other domesticated birds do, so it's hard to have problems of a "sexual dysfunction" nature.

Whatever the problem is, somehow the roos' swimmers aren't getting to where they need to be. If all the birds are healthy, then there shouldn't be a problem with fertility, although a touch of frostbite, or some other stress months ago can be all it takes to throw things off.

Considering that it takes at least 3 weeks to remove all sperm from a particular roo in a given hen's system, you shouldn't be having any problems at all. If the roos are covering the hens too much, that might be a cause of stress to the hens, which can be enough to throw things off. But then again, if they had damage from treading, you would have mentioned that - a 5:1 ratio is a bit too many roos, but within the bounds of reasonable, if the hens aren't being hurt.
Based on what you're saying, I would say that removing the bantam roo might help the situation, allowing the 2 RIR roos to cover the hens.  There's nothing wrong with your bantam roo, so if you like his genetics, leave him in the mix. I wouldn't expect him to really stand to more than 5 hens, anyway. A standard sized roo can easily cover 7 or more hens, which sounds like what the actual breakdown of the flock looks like, so I'm back to wondering what's going on.

I currently have 5 roos over roughly 15 hens. It's a screwed-up mix, but the roos have their smaller flocks of hens who like them, and a couple of the roos serve as "floating bachelors" like you might see in a wild elk herd. The hens are safe and happy. I have a good mix of genetics, so I'm happy. I also have a bunch of chicks coming up, so the new pullets do help boost numbers for the future, which helps. Multiple roosters can and will work together without fighting and without overstressing your hens. It's probably not your set-up.

I guess we have to look at the eggs next.
I had a problem about a month ago when one of my incubators started acting up. It had an auto-program that was supposed to rotate eggs and keep the temperature and humidity at certain levels. It started hitting 105F randomly, killing the eggs inside. To all appearances, it was working fine, but the spare thermometer I had stuck in (because you aren't paranoid if things do go wrong) was able to explain things.
Are you sure your incubator is working correctly?

Are the eggs clean, and gathered quickly after being laid? Are there any conditions that would possibly lead to them being chilled before you incubate them, or kept at too high a temperature before they are put into the incubator?

Are you waiting to recandle? Do you candle at 3 days, 5 days, 10 days before deciding, or do you have a certain span you use that works for you?

I think it's a problem with the eggs, not the birds. From what you've said, your birds are in good health, aren't stressed, and things are fine. If that's all holding, then it's something with the eggs.