So far, I just need to open Firefox Fenix and it happens.
Be able to share to my other devices with Sync activated.
I do not see other devices.
_Note_: I am having many problems with #3877 and, even right after logging in, the other devices do not show up.
Same here (I also have issues with #3877), device Pixel 3, Android version 9.
I is happening since some time, I don't know exactly because I frequently stopped trying to share to other devices because of #3877 being a major PITA.
A similar issue started happening me within the last couple weeks as well. I'll add it here rather than make a new issue
In my case, the "send to device" menu does appear, but it just says "Offline" despite clearly having this device online and other devices online, all signed in to my firefox account
Android device: LG V20, non-root, non-custom ROM stock Android 8.0.0
Fenix build: Nightly 191224 18:02 (Build #13581811)
For the record, the feature still works fine in my baseline FF Preview with build info:
3.0.1 (Build #13502256)
馃摝: 24.0.0, 968f858c1
馃: 71.0-20191125115111
Closing because this is very old. Please open new issues if this is still happening