I'm desperately trying to mount an SSD plugged into an external enclosure on my laptop, but every time I try, it loads (4 partitions), then immediately unmounts. No error message is given -- all I see is basically "has been loaded" followed by "has been unloaded".

I know the SSD is at least reasonably good (based on SMART testing), but I want to run disk check on it to be sure. And it mounts acceptably on my desktop, where it's the system disk for 64-bit Win 10 Pro (1903). The problem there is that it runs unacceptably slow, so slow that chkdsk never really gets started (and all other apps run slow, too). Thus my need to mount it on my laptop. The external enclosure is rock solid -- the best I've ever had.

What's going on and how can I fix it?