Hi again @dnowhere.
That's very strange. I'm sure @yang will know the answer.
I did find one reference to a vaguely similar problem (not involving Core Shell) where it was suggested that rebooting the server solved it - at least temporarily. If you're able to eliminate this I guess it could help.
Sorry - I'm not being of much assistance.
I'll be interested to see what turns out to be the cause.
Keep safe.
Jonathan