I just ran into this problem. I downloaded a bunch of operas to my Android phone before a long car trip. Most opera recordings have many tracks that run directly into the next track, with no pause or silence. Unfortunately, when playing the mp3s through my phone every track ended a couple of seconds before it should have. It's really easy to tell with opera because more often than not you miss the big money note the aria has been building up to.
I seldom use my phone this way, so I thought it might be a "gapless playback" setting in Google Play Music. I could find no such setting, so at the hotel I downloaded VLC and something else called The Unpopular Music Player. I also looked through the phone's settings, but nothing I could do would make the tracks finish completely. I had my notebook computer with me, so I installed MC21 and even MC stopped playback a second or two before the track should have ended. I have to conclude that the end of every track was chopped off when I converted and downloaded the files to the phone.
I had done this with MC21.0.76. If I had any gapless options checked, it would only have been "use gapless for sequential album tracks", and only because I don't understand the options. Years ago when I first tried iTunes I found it useless for classical music/opera because it would insert a silent gap between every track. I assumed "gapless" means the player should not do that. I certainly don't want it to remove any gap that should exist (such as between tracks on a pop album) - I simply don't want it to insert a gap where none should be. In any event, the gapless settings should not affect the actual files when converting from FLAC to mp3.
I haven't had time to do further testing, but I'm convinced that when converting from FLAC to MP3 and copying down to my Android phone MC21 chopped a second or two off of every track.