While I haven’t followed this topic for a while (and there’s no way I have time to read through it again 
), I’d like to take a shot in the dark and share what worked for me way back in June of last year. I haven’t experienced this issue in any release since 5.5.
In the file explorer, navigate to your project folder and delete the following items (no risk here, these will get re-built once you reopen the project in the Studio):
Then, try downloading the latest release (5.10.1 still I believe?) and open your project (it may take longer than normal to open, as you’ll see that these 4 directories are getting rebuilt, among other things), and run your script(s). @Russ_Thomas I’m curious to see if that makes any difference for you, as I’ve used it as a cure-all of sorts whenever the studio is acting strangely. Again, a shot in the dark, but it works for me 