I had the same symptom. When I launched cryptomator on my Windows 10 machine runnning cryptomator 1.6.10, it only showed up in the taskbar. Clicking on the taskbar wouldn’t launch anything.
I had installed cryptomator 1.6.10 a week early and it worked fine for a week (so I don’t think it was a problem created by a new cryptomator version).
My cryptomator vault reads my google drive via a google drive desktop application. What I discovered was that I could not launch the shortcuts to the google drive directories where my vault was stored from my Windows file manager, either. There was a problem with the setup, it was trying to launch a different google account that did not have access to the files (I have multiple google accounts on the pc)… I ended up removing the google drive application and then reiinstalling it. That fixed the problem where I could not launch google drive shortcuts from windows file manager, and it also fixed the problems with cryptomator launching.
Summary: I think in my case the problem was with my connection between my pc operating system and my cloud drive provider. If I can’t access the files from my windows file explorer, then I can’t expect cryptomator to access them either. After I fixed it to regain access to the files in windows explorer then cryptomator worked normally. Before that apparently cryptomator would get stuck during startup because it could not access the directories to display my vaults. Your case may be different.