I have the same problem with 2 brand new Grand Canyons. They work fine on a Boss power board but flash stupidly with no sound on my beringher board. I have 20 pedals that all work on both boards but not the GC.
I have tried various configurations including the pedals on their own. It is quite definitely an EXH fault!

I going to go back to the TC electronics Flashback if there isn’t a simple resolve. The Flashback is excellent, I just fancied an alternative for variety but wasn’t banking on the unexpected hassle.