I recently acquired my own mash tun after sharing with a buddy of mine for the past year. it's an identical setup to his (10 gallon round igloo & stainless steel false bottom), with the exception that I opted for a high temp hose for mine and he has a reinforced braided hose in his. we used his setup dozens of times without issue. all four times I've used my setup, I've had a stuck mash.
I typically brew with a bit of rye (10% overall at most), but that was on the old and the new system. my buddy thinks maybe my hose is getting crushed under the mash, but I don't think that's it. I'm noticing a LOT of grains under the false bottom when I clean up afterwards. I don't know how it's getting under there, unless the more flexible hose is allowing the bottom to flap?
mashing out and even dumping my sparge into the tank hasn't been enough to loosen it up, I've had to dump the entire mash tun in my boil kettle and strain through the bazooka tube. I'm sure this isn't as efficient for straining and I'm getting the smaller particulates into the boil.