I have Firefox installed on a few devices including my two phones, as well as it being my primary Windows desktop browser. My older phone is currently running 121.0 #2015991663 and sync works fine. My primary phone is running the latest version from Gplay store 135.0 #2016070975 and nothing I do can persuade it to sync. I tried logging out of my Mozilla account on the phone, clearing cache, closing all tabs and restarting the device. It now persistenly says Last synchronised: never It simply will not sync.