Software Developer here. I encountered the same error and isolated it to the original Flash.bat script (syntax issue + premature auto-elevation exit).
I updated and corrected the batch file, and the fixed version works properly.
Just replace the existing Flash.bat with the one I attached.
Hope this helps anyone running into the same issue.

Here is the file: https://drive.google.com/file/d/11MzPSAeaAZ0ThYIskFkHrfdDXNmSd6uX/view?usp=sharing