Chord on chord track stops suddenly, but only when after cycling

Just putting this here, as I suspect it’s a bug.
I have my track on cycle, with an 8-bar 4-chord intro.
The first chord after the intro, at bar 9 is an E.
The second chord after tat is 2 bars later at bar 11.
If I start playback as normal, the E sounds until the next chord 2 bars later, which it should.
If however playback gets to the end of the cycle range and starts again, the E stops suddenly - it maybe lasts for half of one beat (what we call in these parts a quaver). It’s like a staccato chord.
Only that chord, out of all the chords in the whole section being looped (at a guess, roughly 40 chords).
Very strange.