The window will open but the map of all the regions does not appear, is there a way to fix this?

It sometimes happens that it won't appear, placing it on the right side of the screen and pressing windows button (and then closing it) usually fixes it for me.

However if you did a lot of painting and stretched the region map by a lot, you're out of luck. It always goes black when too much has been added and there's no fix for that afaik. You can still see what you're pointing at bellow the screen so you can still "paint", but it's kinda annoying.

fixed it, turns out that if i click a random region, it will show, very strange

thanks anyway though

Just watch out as "clicking" random region usually means painting it, and then you have dirty stuff to clean in your plugin. So each time you do it try to remember to always click on your own region and not the one from Morrowind.