ffmpeg runs for non-altered and old videos

Hi,

I have a question about ffmpeg.exe creating thumbnails.
Whenever I refresh my library of files, ffmpeg runs for files that have been in my library for quite some time, even when they were not altered.
The problem ist that it are never the same files.
Can serviio only save a certain amount of thumbnails and can that amount be set to a higher count? (Right now I have a little less than 4800 videofiles)

Thank you in advance
Greetings
IG

€dit
Sorry might have been better off in the Support section.

[zip]

there is no limit. ffmpeg will be run when you refresh metadata via the button on the metadata tab in the console