Hi @Abhishek Dewan I have the same problem here. The error code 1307018 was shown when I tried to sync from my Mac.
I tried:
disconnecting, reconnecting --> no success
disconnecting iPhone and Mac, deleting the vault on the nextcloud, connecting the Mac again --> no success
disconnecting iPhone and Mac, deleting the vault on the nextcloud, connecting the iPhone again --> error code 1308413
Can you help me out with this issue?