GPIO for Opensprinkler Pi

I am trying to run Open Sprinkler on an extension board on the same Raspberry Pi 3 that is installed on. I was able to get the Opensprinkler software installed (I think) using the add-on Slaheij made here:

I think it worked because I can access the Open Sprinkler interface via the default port. However, the add-on log says “failed to open GPIO” and I cannot actually control the relays. Is there anything missing from that would prevent something from using the GPIO? Or something else that is already using it and interfering here? Or something else I might be missing?

For reference, the Open Sprinkler board I am using:

I guess you’re using HassOS since GPIOs are not functional in the current version 1.9. I’m also waiting for this to be fixed.
There seem to be fixes available but not integrated in a release, yet.

Yes, I also moved backed to ResinOS to fix this issue in the meantime