MKV artwork won't refresh

[TurbinesAreAMust]

I use Plex.
Plex uses a specific naming convention so that artwork appears on its server.
You add "-1" for poster artwork.
You add "-fanart" for background/landscape artwork.

Example:
Superman (1978)-1
Superman (1978)-fanart

I use MKVTOOLNIX Header Editor to update the artwork for select movie files. However, the new artwork must retain the same name as the older/replaced artwork in order for Plex to read it.

However, when I open the movie file in VLC and hit CTRL+I to check if the artwork has updated to the new version, it continues showing the old artwork version. I can't figure out how to flush the cache or whatever is going on.

Why does VLC continue to show the old metadata artwork if it's no longer embedded in the MKV file?

[Lotesdelere]

Reset the cache (the manual way) and try again:
https://wiki.videolan.org/VSG:ResetPrefs

[TurbinesAreAMust]

Thank you!