I have two SDK addons that use simple-prefs. Since update fennec 50>51 they do not display.
e.g. This one: https://addons.mozilla.org/en-US/firefox/addon/jolla-askbot-unseen-posts/
I raised a bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1334695
I expected this to be quickly confirmed but it hasn’t been. Is anyone else seeing it? Maybe it’s just my devices - all are all quite old - AOSP 4.4 and 5.1.
I installed an addon yesterday and it shows no options either so it’s not just my own.
(I have webextension versions of both my SDK addons but options_ui is not implemented on fennec yet: bug 1302504).
Added: I discovered that it’s not just SDK/simple prefs. All prefs do not display in Fx 51 for Android for me.