I have Director 11 and I think this is my last project with it, so I don't consider an upgrade to 11.5 since I don't see any future.
I have a serious issue when I paste text from Word or even Wordpad. Sometimes it erases spaces between words.
I want to keep some formating because I have a lot of text so pasting from Notepad it's excluded.... too much work
Director 11 was a pathetic, miserable thing. Director 11.5 fixed many (not all, but many) of the problems introduced in D11, including a great deal of the text related issues that came with the new text engine. I do not know if D11.5 will work better in your specific instance, but it is useable. In my opinion, D11 is not usable, and never should have been released to the world.
Anyway, I would recommend that you download the free trial version of D11.5 and see if it works better. Beware though, that you need to do it on another machine that does not have D11 licensed on it. It will probably overwrite the D11 installation, so you do not want to do that if you do not plan on purchasing D11.5.