I had the same problem:
If your on a PC, open CMD in admin mode:
run DISKPART
LIST DISK
SELECT # (# is the number corresponding to the 512GB microsd)
PLEASE BE SURE TO SELECT THE CORRECT DISK, THE NEXT COMMANDS WIPE DATA!
CLEAN DISK
CREATE PARTITION PRIMARY
Exit the command prompt, use Win32DiskImager to write the 1024K image-file to the microsd, re-insert the drive into the PC and windows will ask you to format it. Do a quickformat to EXFAT and 64K clustersize. Note: the vita understands ExFAT, but anything over 128GB needs 64K clustersize.
- note : the sony memorycard needs to be uma0:, the sd2vita needs to be ux0: - just use "TF.Card.Plugin.Tool.vpk" and make it so.
This, worked for me, proof:
View attachment 246517
I will try and let you know , Thanks