First of all, please make sure that you name the file correctly. As WALTR 2 gets the artworks directly from public media sources (like IMDb, Spotify, etc.), it is crucial for the file to have a proper (official) name.
There is one more important thing to understand: when it comes to transferring an artwork, WALTR 2 first looks for an image injected into the video file. If it’s not there, it looks for an artwork in the same folder as the file. And if it doesn’t find artwork in the folder, then it looks for it online using the name of the video.
What if the artworks are totally messed up on my device?
In this case, please check if you can see correct artworks in the moment of transferring right in the WALTR 2 window.
If the answer is yes —> then the app pulls metadata correctly. The artworks get messed in the device's library for some reason. When this happens, you can delete the files previously uploaded with WALTR 2, and transfer them back. This can solve the issue.
Anyways, shoot us at firstname.lastname@example.org and we will try to help you.
All the best!