Hi,
Thank you for update, this is really interested especially as I could not replicate on any of my devices.

Well, I continued my investigations and discovered it is something to do with Volume Serials. I eventually put the 128gb card in my old Umidigi phone. It wanted to format it again so I allowed it to and the card now has a Volume serial of E709-17F1. Putting this back in the Moto G6 Play everything is fine and it is now consistently recognised as the same card.

It would appear there is something wrong with the G6 Plays formating of a 128gb card. I have no idea how a card gets its volume serial and I am not risking giving the card a new volume label since it works.

Hello,

I have a Moto M6 play with a 128gb Samsung SD card in it. Each time I reboot the phone I have to grant access to the card again and when I look in Library folders it adds a new entry. So having rebooted a couple of times I have 46443045-2d31-3339-3000-68af4000068af and 46443045-2d31-3339-3000-78b4400078b4 as well as the newly granted music for the Samsung SD Card.
Since I want to add 100gb of mp3 files this is a major problem as the library rebuilds each time adding duplicate entries of all the tracks it already knows (15000 tracks a time). Am I missing something that I can do to stop this?
I have tried formatting the card in the phone. I have also tried making it "internal storage" but the phone seems to lose the card completely which seems weird so I am back to formatting as "portable storage" which I prefer anyway.