Same Issue. Music disappears, then reappears anywhere from seconds to a minute later and then reads fine. Card is about 2 months old. Pulled right out of my old phone. Put the card back in the old phone and no issue.
Contacted online chat. They would not acknowledge this forum topic even though I linked it. Had me troubleshoot in safe mode. Cant use any of the music apps in safe mode ( Jet Audio Plus and Play Music). Did however experience the Image Gallery flashing and then reloading, so it still happened.
So they opened a trouble ticket and sent me to phone support. Was on hold for 15 minutes. FInally got through. Explained the situation and referenced the ticket. Mentioned the troubleshooting and also this forum topic. Their answer is go to a Samsung Experience Store at Best Buy and let them run a diagnostic.
I'm a heavy SD Card user and don't have time for this crap. WTF.....I have a week to return the phone. Just acknowledge the **bleep** issue and tell us if there is a fix on the way.
I guess I can add my S8+ to the list with memory card issues. Verizon told me bedded onda of their cards. My card relatively new, less than year old. High quality. Not happy. Music and ringtones on the card.
Checking in; I have also had problems with my SD card. I'm using the 250 GB from the Immersive Experience bundle. Random mounting/unmounting - extremely annoying! I couldn't be more pleased with the Gear VR or S8+ performance, however; and it doesn't seem to unmount when data is actively being accessed (games, music, VR, apps) which is promising. I really hope this is addressed soon... I'll call Tech Support later this week if no fix is mentioned
After a day with no SD card and no problems, I took the plunge and put in another card (brand new SandDisk 64gb).
Fromatted it, then transferred photos and music from the internal memory to the SD card - same problems as before (greyed out placeholders, photos taking 30 seconds to open (& then being ½ greyed out), music stuttering etc.
Took the card out, reinserted it a number of times, same issues.
Took it out 1 last time and then very carefully and slowly put the card back in the tray - just like a dozen times before. Looking closely I could see it wasn't sitting quite flush - it felt ok with when inserting it, but it didn't seem to sit correctly.
I fiddled about for some time, taking it in and out and finally was able to place it perfectly flush with the holder in the tray. The tray also slid in and out of the phone much more smoothly.
I cleaned the card contacts with a micro fibre cloth and slowly, carefully inserted it back into the phone.
I can report that for me, on my phone, this method worked. Reformatted the card, transferred music and photos across - and it all works perfectly. Photos open instantly, no grey placeholders, no stuttering music. I can listen to music and take photos - without thr music app crashing.
I've tested it for just over a day now - everything going perfectly. At last. Took a lot of time, a lot of frustration, but it works (for me).
On my phone, it seemed to be that the SD card didn't sit correctly in the tray - or that it has to be placed in very carefully in the tray.
Interesting, so it's literally showing on the monitor as simply mounting, unmounting, failing, and repeat over and over. Has anyone else checked how the tray is sitting inside their phone like @userf9MplVzlnQ did? I'm wondering if perhaps it's SUPER sensitive with how it's seated, and the smallest amount of offset is making those contact points flick over and over.