since update to version 1.5.11 cryptomator doesn´t mount the drive neither automatically nor manually. So in Cryptomator I see the decrypted and mounted drive but not in explorer. So you have to terninate Cryptomator and close the drive and start Cryptomator again, then everything works like usually.
I have the same problem. After booting my pc I unlock 4 vaults in the cloud. One by one after unlocking and reveal in cryptomator looks normal. But with the Explorer the unlocked vaults are not there. With cryptomator, btw 1.5.11, I locked and unlocked the vaults again and the vaults are just normal in the Explorer. So without quit and restart cryptomator and lock / unlock it looks good. At first I locked the vaults quit cryptomator and start it again unlock the vaults just normal working.
The pc is running
Windows 10 Home
Installed on 07/06/2020
OS build 19042.789
Experience Windows Feature Experience Pack 120.2212.551.0