As of the last update in Studio, the GuiRoot is visible in the CoreGui:
When it’s selected, it errors multiple built-in plugins:
This has been happening for a while now when selecting locked Instances (the best example being CSGDictionaryService), but as of this recent update it’s more easy to cause because GuiRoot is easily visible. This happens every time anything that’s locked to these plugins are selected. The expected behavior is that they don’t error.
Ideally this would be changed rather than patched in these particular plugins, as other plugins I have installed error on selection too and it’s a tad annoying, but if this were changed in the built-in plugins it would eliminate the main problem.