In Firefox for Android (latest version, 60.0.1), Firefox sync does not work unless Privacy->Firefox Health Report is enabled. If you disable that option, using the "Sync now" button never updates the "Last synced" time (yet it shows no error). Note: after toggling Firefox Health Report, you have to force stop Firefox (from Android Settings->Apps->Firefox) for the change to take effect. i.e. disable Firefox Health Report, force stop Firefox, re-launch Firefox, then try to sync. It won't work. Re-enable Firefox Health Report, force stop Firefox, re-launch Firefox, then try to sync. It will work. Note that I am using a self-hosted sync server instance. Everything works fine as long as I don't turn off Health Report. For the sake of improved privacy, I spent a great deal of time & effort migrating all my devices from Chrome to Firefox, and setting up a self-hosted Firefox sync server. Is there a reason Firefox won't let me sync my data...unless I let it send data back to Mozilla?