Tor Browser is preventing add-on from saving its setting
TL:DR; I've downloaded an add-on from mozilla, and when I try to configure it the TorButton cleared its settings.
Detail: First, I thought this might be an add-on's bug. I tested the add-on with Mozilla Firefox ESR and Firefox 57. Both worked without problem. So I removed the add-on from Tor browser and tried this. When I clicked "Save", it cleared all forms. The Browser console said TorButton is causing this issue.
I understand you don't want users to add any add-ons to your browser. But isn't this too much?