[ScorpioJonesy]

I am have a lot of trouble getting thumbnails to display correctly on some of my media clients. I have a central Windows machine with a kodi (v18 RC1) install and all my media (shared via SMB) along with a MYSQL. I then have some other Windows and Andoird TV clients (v18 RC1) all using the same MYSQL and all able to access the media, watched status and resume points all work between them. Often though thumbnails wont display unless I go into the movie / show and refresh it.

What is the preferred way to get around this problem?

[Klojum]

What is the preferred way to get around this problem?

You have one computer fully up-to-date as far as thumbnails goes, and copy the Database/Textures13.db file as well as the Thumbnails cache folder to each of the other Kodi clients and have them reboot.
Other than that, and after that, each Kodi client will update its own thumbnail cache as necessary. Are you using pathsubstitution to a common network location for your thumbnails?

[ScorpioJonesy]

What is the preferred way to get around this problem?

You have one computer fully up-to-date as far as thumbnails goes, and copy the Database/Textures13.db file as well as the Thumbnails cache folder to each of the other Kodi clients and have them reboot.
Other than that, and after that, each Kodi client will update its own thumbnail cache as necessary. Are you using pathsubstitution to a common network location for your thumbnails? 

 OK I will try the textures13.db trick. In terms of pathsubstitution  I did look at it but wanted to know if that was the a good idea. I have a "thumbnails" share which I can point all the clients at if that will work.