in my resource pack i have replaced multiple music discs with other music, but at some point an update caused some of them to cut off seemingly at random while the song is playing. i did some testing with the discs i found cut off and although it was a little hard for me to tell i believe that what first seemed like random stopping is actually not and the discs cut off at around the same time each playthrough. therefore my working theory is that at some point an update was made that caused discs to only run for the original song length rather than adapting for the custom song length as had been the case for ages prior.

for example, i replaced the music disc "mall" which is 3 minutes 18 seconds long with a track that is just over 4 minutes, and the custom track cuts out around the time it starts getting to the end of the song. as i have mentioned before this is an issue with multiple other music discs in my pack, and i would hope this bug gets fixed at some point in time.