Hi,
I would suggest reducing the size of the program until it starts working again - and then at that point you might start to get an idea of where it goes wrong.
If you’re able to create a short example of a bug I’d be very happy to look into fixing it.
Additionally, be aware that between v2 and v3 cue and sync were rewritten to make them fully deterministic. In v2 and before they had race conditions which meant that the behaviour could change with successive runs. It’s quite likely that this change has effected the behaviour of your program. If this is the case, please accept my apologies. However, things are much more likely to be stable with your code going forwards.