How to fix missing artwork

Hi

Same goal here. more than 5000 movies. Updated from Kodi 16 > 17.
a lot of posters/fanarts doesn't show up, and at first glance it concerns old scrapped files. Problem is in all skin.
each movie is in a separate folder, and in the folder there are the usually extrafanart (extras show up, problem is only with basic poster/fanart), and of course local poster/fanart pictures)
Deleting Texture13 and thumbnails didn't solved anything.
importing single file library keeps the problem.
importing through sources, with local information scraping, same problem.

I guess there are some problems in the old NFO's.
I don't want to rescrape online all 5'000 movies, it would be a nightmare to control everything.
the solution so far I found is to refresh manually such problematic movies, or manually select local files when the data is not retrieved (unreachable scraper)

I hesitated to bulk delete all NFOs, then export library as separate files to create new ones, but I don't know if it will work and it may be a bit risky

Please tell me if you find a solution