I used Agfa's modern Rodinal for about 18 years and it never ever crystallised. I also used a lot of it as I was processing 120 but mainly large format negatives, that sounds like a temperature problem with Sulphite crystallising.

There should be a very very small amount of crystallisation in the old Rodinal/Rodinal substitute formulae because that's how it's supposed to be made, no excess Hydroxide so just a trace of free base crystals.