I don't think anybody on the WireShare dev team has Big Sur OS 11 to test since Apple loves to limit what OS each of their older machines can run.
Whilst this won't solve the problem with the WireShare version you have, you could try a different version to see if the problem persists.
https://sourceforge.net/projects/wireshare/files/
If one of the versions do open and load properly, it gives us a starting point to work from.
At this point I haven't heard back from BigJx.
Edit: Forgot to ask, does the WireShare program 'Get Info' option have any compatibility options?