Preferences not saved

[jbriales]

I'm going to 'about:addons' -> 'Web App Mode', click [...] and Preferences
This opens a new tab like moz-extension:https://c75eac05-9ad0-4f92-9f09-5b75a51ef4b4/options.html
where I can add 'Match patterns'.
However after adding and closing this tab the patterns aren't saved nor applied.

Am I doing something wrong?

In:

• Fedora 30
• Mozilla Firefox 71.0

[GitMensch]

As this is an old issue I guess it is solved, no?
[works fine here]

I suggest to close this because of its old date.