No mention in the help of the get being asynchronous, and the code  looks
straightforward enough.

I do have a concern with your Perm(1 To 20) ...

The help for "get" talks about dynamic arrays and gives as example:

Dim MyArray(1 To 5,1 To 10) As Integer

I don't know if it treats such definitions as dynamic, even though they're not.
The gist of it is that you need to allow extra bytes for descriptors.

Are you in a position to try this with a more "traditional" array dimension to
see if it helps?

The only other thing I found in a quick Google trawl was a suggestion to use
LenB() instead of Len() to get the length  of UsrType.

Odd indeed that forcing a bad  compile is enough to fix the problem for a while.
Maybe there is a bug.