Upon going through the release notes it appears a similar issue happened on Windows and was fixed in 3.8.2.
From Plexamp Release Notes - #35 by elan
Windows: Gray screen on startup.
Following up with the thread relating to that issue it appears that it was also related to the treble.node lib.
The eventual fix, Plexamp 3.8.0 starts up with an empty window on Windows 10 - #31 by elan, seems to have been to include a missing DLL. I’m not sure if this is a result of changes to how the module is built or not, but it might be.
