Pairing with Bluetooth-Headphones fails

[juri.gagarin.ii]

Good day to all!

I have a problem, but I do not know if it is better here or in the iodé forum… I’ll try it here for now:
I have a pair of Grell TWS/1 (Bluetooth in-ear headphones) to test here. There are two smartphones available for testing, but stupidly I still can’t test them because:

1. pairing with a FP4 works fine, but there is the test build of CalyxOS on it. I can pair with it, but the Bluetooth codecs are broken. So it pairs, but I don’t hear anything.
2. pairing with a FP3 with iodé does not work. At the beginning the headphones said: “Pairing failed” and on the FP3 always popped up a message that the PIN was wrong (in the lower part of the screen). Normally I would expect a dialog box asking if pairing is OK. But that does not appear. I then reset the headphones and also the Bluetooth settings on the FP3. This actually changed something: the error popup no longer appears. However, the headphones still say “Pairing failed”.
   Is there anything else I can try?

By the way, I can pair other BT headphones, that’s not a problem, it just doesn’t work with the Grell.

[Volker]

You might (temporarily) replace the test OS with another one (e.g. stock OS) and test then or you might use adb logcat to check if you find something helpful in the output.

[juri.gagarin.ii]

I don’t dare to replace CalyxOS on the FP4, because I don’t want to brick it
But I could try adb logcat when I have access to a computer.
Thank you for the tip.

[juri.gagarin.ii]

I guess sometimes all you have to do is make a little bit of a threat that you’re going to get to the bottom of things now.
I just installed Logcat Reader from f-droid and ran it without root. I just wanted to see what you could see without root. And what happens? What did not work 20 times before: the headphones can be paired.
Strange.
I mark your post therefore as a solution, although it was more like a metaphysical solution