songs cutting out abruptly mid-track

[coldbeer]

Songs are stopping abruptly before the track is finished, then the next track in the playlist begins. This is happening on an Android (LG G6) for all songs in my library and playlists (many of them are downloaded). The timing of the cut-off is not consistent but it's usually when the song is about 75% played. If I go back to the (partially skipped) song manually I can play the rest of the song.
Why is this happening and how can I fix & prevent it? It's very annoying.