I've been having the same problem ever since the update few weeks ago. Sent a message but to date no response from Samsung.. My Sd card works fine in another phone so the issue must be within the software update. Very frustrating.
Just to whom are posting in this thread to try to help solve this can you put some details such as phone / card maker and size / if you have formated the card (quick or full format)
Mine is note9 128gb
Card that corrupted was a sandisk ultra 128gb
Card was not formatted before putting into note9, was used previously with S9+, full power off before switching card over.
New card is Samsung Evo select 256gb with full format, followed by format inside phone - NO ISSUES YET.
Just an update on this.
With the new card I've had no messages at all and the old card has been working fine again in another device after passing a full H2TestW scan.
The only thing I can assume is that the note 9 CORRECTLY reported corruptions in the card that occurred whilst it was inside S9+.
Whilst its annoyed me that I've lost a few videos, I'm more thankful that the image backups were all perfect and managed to recover all my images.