I am so glad to have found this thread! I too am struggling to find brown cane sugar that doesn’t turn into rock hard clumps! An interesting thing I learned a few years ago is that while cane sugar and beet sugar are chemically identical they cook differently. When I make oatmeal cookies with cane sugar they come out with some height and with beet sugar they are flat and look crystallized. Lately I have noticed that even though I am using cane sugar they look like I’ve used beet sugar. Plus the brown sugar forms rock hard clumps that make mixing the batter ridiculously hard. It’s almost as if beet sugar is being substituted for cane sugar. I use exclusively C and H cane sugar and something has seriously changed. When I have mentioned it to my friends they are say, Now that you mention it the brown sugar has been weird!