Ignore everything after this. I was stupid and did not notice my brush strength was zero.

I’ve been working on a rig for a model, and I’ve gotten to the weight painting stage. Given that I’m relatively new to rigging, I’ve had to restart the process a few times. My most recent weight painting endevour is the farthest I’ve gotten, but the tools suddenly stopped working.

What can cause a properly parented and posable model and rig to no longer accept weight changes?

I’ve tried selecting all the vertices. The vertex groups are unlocked. Accumulation has been turned on and off several times. Subdivision is off.

[Update 1]

So blur, average and smear work, but the main paint brush simply refuses.

The new link should be a .mkv file in Google Drive