Yes, I agree that it's not comsistent. I can't work out what the cause is either. For some reason, I'm finding the joins with FLAC better. By click, I don't mean a loud 'tap' but a 'tick' when the track changes.
Gapless isn't as successful as I'd like, so I rip long seamless albums as one track and leave out track names etc. if I can be bothered. Downloads seem to be worse in this respect.
X3 does it too.
didn't test enough variables for gapless on the X1, as I also go with 1big file for anything live or most classical music when in mp3(and when I really want tracks and .cues don't work, I just go with flac for that album). a habit coming from using several DAPs that couldn't get a good enough gapless for mp3 whatever I would do, use lame, go VBR instead of CBR try to mess up with the padding, always rip from CD instead of already ripped files...
in the end stuff like foobar and rockbox come real close to perfect gapless mp3, but that's mostly it. so my answer to people is usually to use another file format for what they want gapless, or to make 1 single file.
ogg had an answer for that I believe, but I just gave up on ogg for music because not enough DAP would bother to do it properly. so flac is probably the best choice nowadays for gapless, as there are no delay/padding stuff, so the DAP only has to buffer the next song soon enough and not cut the signal between tracks to pretty much become gapless.
I would expect a "tick" noise from DAPs cutting the output signal between tracks, so silly question, but do you have gapless set to "ON" in the settings?
(again I'm talking from usual situations only, as I just did 1 test on the X1 for my crappy but long review and went back to using 1 file for what I want gapless as I'm used to do).