in a small triangle to the right of the brush settings it makes it so you can reset default brush settings or something. click that every time you switch brushes i dont know how to fix it totally but you can manually switch it. hope it helped man.
"Restore default variant" did not work. However, I put one in a different brush category and opened the brush editor on it. It started working after that. But this didn't work on the separate brush groups I added.