So, I’ve tried a couple of things to no avail.
First, I commented out a few plugins in the app.yaml then rebuild. No change
Then, I put those plugins back in and removed others. No Change.
I’ve now gone into safe mode and it’s still doing it.
On my laptop it’s fine if I’m not connected to the external monitor (same monitor my PC is using) However, if I connect to the external, then it blanks as per my original issue.
One may chalk this up to the external monitor being the issue here. However, it only happens with my forum, and I wasn’t the only member with the issue. So, it could be some weird combination of hardware and software that we had in common.