Upgraded from 1.5.3 to 1.5.4 Vault format conversion now files not showing but are still there on harddrive

Hello,
I recently the other day upgraded from v1.5.3 to 1.5.4. On one Vault only (1 of 4 Vaults) v1.5.4 ask me to convert to the new vault format. Actually this specific Vault was created under v 1.5.0 a few weeks ago so it was a native Vault format 7 from the start. I proceeded with the conversion and no errors appeared and it looked like it went smoothly.
I then unlocked the Vault and revealed it but there are now no files showing. I can still see the underlying encrypted files are still on the hard drive.

Win 10 Pro, x64, latest updates.

Please advise what to do now?

Cheers

A vault created with 1.5.0 does not need to be migrated. When you open the masterkey.cryptomator file with a text editor you can see a version entry.

This entry must have been 6 in order to migrate a vault. Even if one used the first alpha version of Cryptomator 1.5.0, it createed a vault of format 7.

Do you have a backup of that vault?

I checked the masterkey.cryptomator files. I had 1 masterkey.cryptomator files, 3 backups and masterkey.cryptomator-PC_Name, the last one appears to be some conflicted version from OneDrive. One of the backups had a Version 6 as entry. I replaced the active masterkey with a backup from about the time I originally created the version 7 vault, this backup was Version 7.
I opened the Vault and all files are now visible again.

It appears, although I can not follow how or why, that OneDrive, where my vault is located replaced my new good Version 7 masterkey.cryptomator file with my old pre-upgrade verions 6 masterkey.cyrptomator file. Therefore the Cryptomator App thought that it was an old version 6 format and asked to upgrade to version 7 format, but in reality the vault format was already a version 7.

Thank you for your support and advice.