zigbee2mqtt on CCU no joining of new devices

[akegg122]

Probably I am completely wrong here but sorry, I´m new in GitHub and don´t know where else to put my experience report.
zigbee2mqtt is a super tool for me and has been working properly for about 2 months. Since 3 days I had some problems that are solved now but I wanted to report them because maybe they might help the developer or others.
Setup is a raspberry Pi with raspberrymatic newest versions installed. Zigbee-Stick is a CC2531 .
My problem was that I could not create a network map anymore and I was not able to add any more new devices. All installed devices worked properly, so I believed the hardware was not the problem. Interesting was, that by activating the learning mode I got a message that is has been started, but the countdown timer did not start as usual.
I deleted one device after another (specially the routers because I did believe it was a problem of them), but nothing helped. I rebooted the hardware every time. In the end I connected the Stick to anoter USB what didn´t help either, but after connecting it back to the original USB it worked again. I Use CuxD and have set the parameters.
Maybe this helps someone and I hope, the admin will move this post to a useful place...
And...Koenkk...as soon as I can support you with a little amount of money I will do so - but please via PayPal if possible...

[akegg122]

...and now it happens again - joining mode pressed in the frontend, message appears that joining is possible but no joining is working, no countdown timer, no network map but all devices are reachable