App version: 2.3.2
Samsung Note 10
ExoPlayer is selected (as recommended)
On the lockscreen, the rewind button is always disabled and does not work. The other two (play and forward) work ok.
The same behaviour with or without Bluetooth headphones.
I dont know if you have tried this already.
You can got to the App Settings > User Interface in the External elements section and tap on Set Compact notification buttons.
There you can pick which clickable buttons you want to be available in the lockscreen. You can only pick two extra options besides the play/pause button.
Already done that, Fast forward and Rewind are checked, but no effect on the lock screen