How to make "Genre" field visible in my car player?
Does MP3tag show the genres in the files?
If so, then there is little that MP3tag can do about the features of your car player.
You could experiment a little with different tag versions like V1 instead of any of the V2 tags.
But that is about it.
If your car stereo has no function to show the genres, then there is little hope that you can add that feature simply by tagging.
I honestly brand new with mp3 tagging...
I tried to change the syntax from %genre% to $meta_sep(genre,\\) in the value field ... not sure if what Im explaining makes any sense
Modifying the display in the column is OK for itself but does not really answer the question
It also does not answer the question whether and how your car player shows genres.
So, first find out whether you have any data in the field GENRE with a filter:
%genre% MISSING
This filter expression will show all files that have no data for GENRE. Ideally, the file list displays no files with this set filter as that means that all loaded files have data in the field GENRE.
You then test the files with data in GENRE with your car player and see how and where it shows the GENRE. If the car player has no such function, then there is not a lot that can be done about it.