I also enter the key in the 'key' field as well as in the title. It can show up in the title caption which, apparently, can allow identical titles in the main library that are modified by the caption field. For example, I have 3 amazing grace charts with identical titles that have differences in the displayed captions. My captions that are displayed are key, tuning, and source. I haven't played around with this because what I'm doing is working so far.
Dell Latitude 13.5" 2-in-1 Ubuntu/Win 11
Samsung Note Pro SM-P900 12.2 Android 5.0.2
Samsung S7+, Android 12
Samsung Note Pro SM-P900 12.2 Android 5.0.2
Samsung S7+, Android 12