Posters and Banners not being shown

Hi, lost here. Tried everything including totally reinstalling all Kodi software and DB on MySql

Environment:

* About 6 devices which have Kodi 16.1 installed and are configured with the advancedsettings.xml to connect to a MySql DB to retrieve and store all multimedia, additionally path substitutions is set up, including setting the path for the thumbs to a NAS. (Only the Thumbs path substitution has for each device his own Thumb sub directory, so no device uses another devices thumb data, as to prevent corrupted DB’s).
* Thumb folder for each device is nicely filled with actors, posters etc.
* All data sources are located on one NAS drive
* When scraping for new content, I have set each source to only retrieve data from local directory.

Problem:

* For some reason, a lot of Movie posters and TV Show banners are not shown in the Kodi Remote App, they are blank.
* However if I just browse through Kodi on the devices screen, all Movies and TV Shows are displaying the posters/banners/backgrounds correctly.

Tried:

* I Reinstalled all devices and did a new DB installation and scrapped all Movies and TV Shows again from local source just to make sure their is no inconsistency between devices and that the DB is not corrupted.

I could really use some help in solving this problem. 🙂

I have screenshots, but can’t see where to upload them.

Thanks for any assistance.