Bluetooth pairing fails, no more PIN entry field

I wanted to pair a bluetooth device (specifically, [Dynamo Harvester](http://be-on-bike.de/de/harvester/overview.html)) with my Moto G 2 (Android 6) with the normal workflow: Open bluetooth system settings, scan for devices, select *Dynamo Harvester*, enter the PIN and it is paired. Now, after entering the wrong PIN (0000 instead of 000000) several times – where most of the time a message was displayed that the PIN was wrong –, I entered the correct PIN, and something strange happened. The *Incorrect PIN* message popped up for a brief moment, and afair the device moved to the list of paired devices. Since the app still did not recognize the Dynamo Harvester, I turned bluetooth off and on again. Now the device has disappeared from the list of paired devices, but appears in the scan list. If I try to pair, I cannot enter a PIN anymore but receive a message *Can't communicate with Dynamo Harvester*. I thought that perhaps the device is broken somehow, but connecting with a Samsung Android tablet worked just fine (with the correct PIN). What can I do? Might this even be a bug in Android because of the strange message about the incorrect PIN, although it was correct?