To be honest, I haven’t yet fully tested on Unity 2020, but of course it is definitely something I have to do.
Also please note that in regards to GC.Collect, there was a fix in recent version (3.0.8+). Are you by any chance using an older version that this one?
In regards to the External Inspector, you are right, thanks! I have just changed the method name so that it does not conflict with the unity native one 🙂