Is there a maximum size that will display? I have a 2020 Octavia and some art is not showing. I had a Seat Leon 2017 before and I think the max size was 500x500 but is it different for Skoda?

I've found that all my album art has to be 500x500.  Anything larger and it tends not to display.  Very occasionally I still find an art cover will not display, but that seems to be more a glitch issue  in the Skoda software - switch back a track and then forward again and the cover appears correctly.

 

I've also found there's an upper limit to the number of tracks/files you can have on an SD card which the head unit is capable of reading (mine's a Columbus unit).  Can't recall the exact number now, but it is several thousands.  You'll know the message when you get it, something along the lines of "too many files" will appear on your centre display but it can take a little while for it to first appear whilst the head unit is scanning in all the files from your SD card.

Yeah I've found that too. I like it can play hi-res flac files. I have some 24 bit 96kHz albums it plays fine. Not sure if it's downsampling or not. Someone told me VAG systems downsample to 48kHz.