Botched blocking

Soil blocking sounds like such an amazing way to grow seeds. My first attempt did ok with 3/4" blocks, but a total fail with the 2" blocks.
I gave up on the 2" until this year. I watched a great video on YouTube, and thought I'm going to try again.
Armed with a new recipe, and new technique I made my 3/4 and started my seeds. I made 2" blocks, and I was so happy. Oh yeah I've got this now. Famous last words. I think I have been over watering, I think maybe my house is to cool for soil blocks.  At least that's my best guess at this point.  I don't think I have ever killed this many seedlings before. To be honest I'm just not sure it's worth the effort.

I wonder if the people who swear by soil blocking are the ones starting hundreds of identical seedlings, so if 20% die, it doesn't matter? I am usually only starting a dozen or less of any particular plant, so I prefer the paper pots.

That said, it's been a weird weather year. I got some seeds to germinate, and I knew they would be slow to grow, but it's been weeks and they've done nothing, and I think it's the too cold/too hot cycle.