Hey @Clander
Thanks for writing back.
As you have mentioned that you have restored third vault of Enpass on other devices except Linux. In that case, please follow the below steps to restore the same vault of Enpass on Linux by using the following steps-
Take the backup of same vault of Enpass data from your windows desktop using these steps. Open Enpass > Click on 'Settings' > Click on 'Vaults' and select the third vault > Click on 'Backup now' given at the bottom > Select the location and save it.
Now login to your Dropbox cloud account on your windows desktop and upload the backup folder in the Enpass app folder.
Now login to your cloud account on your Linux device, download the same backup folder data and save it locally.
Open Enpass on your Linux--> Settings --> Vaults --> Create a new vault by clicking on '+' > Restore the data from the backup file saved locally.
Hope this helps.