Some users said "when the call is ended, the in-call button still remains on the screen".
What's the reason?
There is a bug in the ROM of your phone. When the call is ended sometimes the ROM doesn't notify the recorder, as a result the recorder doesn't know the call is ended, so the in-call button remains displayed.
How to know it's true?
You can test other recorders, the result will be exactly the same - the problem is inside the ROM.
How to fix it?
No good solution, you have to wait the manufacturer to fix it in future ROMs.
How do other recorders deal with it?
I'm afraid most recorders don't deal with it, or even don't know it.
How does Boldbeast Recorder deal with it?
If the call is ended but the button is still displayed, please click the button quickly 3 times, or click and hold it for 2 seconds, then the app will let you confirm to stop recording and remove the button. This is the best solution so far.