I’ve been fiddling around with the step sequences and after a copy-action from pattern 1 to pattern 2 it seemed like it crashed. From that point onwards when I try to enter the step sequencer from a pad (any pad), it either says ‘loading pattern’ or the ERROR CUIVA zynswitch (10,‘B’) or (10, ‘S’) message.
Loading a different snapshot works, even if it has patterns in use. Patterns do play.
It sounds like a bug. Zynthian is predominantly written in Python which, having encountered an uncaught error in a function will avoid running the function again. This probably explains why you can’t access the editor after the fault.
It has been a long time since I looked at pattern copying and many things have changed. Add a bug report and we will take a look.