Hi @Woutcam,
Sorry for the inconvience caused to you.
To investigate further on this issue, I want a little input from side, so please share the following information:
1. Which Enpass version ( Downloaded from Enpass website or Windows Store) are you using?
2. Open OneDrive in any Browser --> Click on Apps --> Enpass -->Check and share the size of the " vault.enpassdbsync".
In case, if you using the website version of Enpass please enable logs from Advanced settings of Enpass. And when the error message occurs please copy the logs and share with us.
Thanks for your co-operation.