Some guitar bends have stopped playing back

I am about 80 bars into creating a Musecore version of Hank Marvin's cover of "While My Guitar Gently Weeps". There are plenty of guitar bends as you will appreciate. I've been working on it on and off for about 3 weeks. Yesterday, some of these bends stopped working in playback; the relevant notes don't sound unless I delete the bend. Most of the bends continue to play back without problems.
I've attached the file and invite comments.
Version 4.4.4.243461245, Revision 2232670