Files showing in wrong folders

I have created a folder titled “TV Series”, that contains sub folders for different tv shows I have on my hard drive. while most of the files remain in the correct sub folders, some files appear in the main "TV series poster. Its never all the episodes, usually just a few of the episodes, but the sub folder then doesn’t appear at all, just the random episodes show up. it looks messy, and then I dont have access to the other episodes in that folder.

I have another folder titled “foreign TV series” which is basically the same as the “TV series” folder, but it doesn’t have any issues at all. I also cant find any similar factors between the files that are doing this, ie they are different video formats, labelled differently, different sizes etc. all file names also match the folder name etc.

Please help if anyone knows how to fix this. they messiness of the folder defeats the purpose of the app entirely for me.

PHOTO DETAILS: you will see all the shows sorted into their folders with the assigned artwork, but in between these folders, you will see the random files IE “S2-E14” or “S1 - E2”.