GarageBand software instruments cut out after a short while but midi keeps recordings

I'm trying to use an electronic drum kit (Donner DED-200) with GarageBand. It works, but the sound of the software instruments triggered by the midi signal cuts out after a short while, 30s or so or possibly exactly 32 midi events.

Midi events continue to be sent and continue to be recorded, just no sounds is played for them. When I play back midi events recorded during the silence they are normal as if the instruments were working fine the whole time.

I tried several different USB cables and hubs. I even tried on both a MacbookPro and an iPad Pro 11 and had the same issue on both!

Any thoughts on how to keep the software instruments from cutting out? It isn't really usable like this. It would be a shame to be forced into the hassle of returning this otherwise pretty good beginner drum kit because GarageBand just doesn't like it.