Just to get things straight:
You created a vault on ChromeOS and synced it to GoogleDrive. You can unlock the vault on all systems (including ubuntu), but on ubuntu no files are shown. On ubuntu you access the vault via GNOME online accounts (see here).
If I’m getting you right, then I have bad news for you: This is a known bug, because your Google-Drive storage is mounted as a remote folder via Gnome Online Accounts. To provide access to your vault, Cryptomator uses the FUSE protocol and using it results in errors. Additionally Google does not provide a sync application for any linux distribution
Just to make sure, can you post a Cryptomator log file of your system?
This is normal, the access point of your vault is randomly generated to avoid conflicts. You can change this by selecting a specific mount point in the advanced options.