The break tool button doesn't toggle when clicked but the change of state (On/Off) is take into account. When it's off it stays off until you refresh the page and vice versa.
When I installed ZAP for the first time it was working correctly but know it's buggy. I don't have logs generated for this thing but I have two HUD errors:
I use ZAP 2.10.0 and Firefox 84.0.1 with Windows 10
Thanks for your work, the tool is amazing.