With regards to the first half of your post (and screenshot), that exact thing happened to me when I published for the first time. The problem in my case was having my mod files as expected in C:\blahblah\Data\etc but also now having the mod in .pak form sitting in my \Documents\Larian\Divinity\Mods\ folder. When both are present, I think the Editor defaults to reading from the \Documents\ .pak file, rendering it largely read only in-editor. Try removing the .pak generated from publishing from \Documents\ and see if it helps.
With the above in mind however, you go on to mention that you've never been able to create scripts, which is not something I've faced. That could be related to an issue with modding the main campaign perhaps, if that's what you're doing? Not sure, sorry.