my first thought had been, that I or my Forerunner 935 had messed up the FIT-file.
But after three interval trainings with missing manual laps and successfully importing the same training converted from the FIT-file to a TCX-file with laps and seeing in the changelog that you had done some changes to "overlapping" manual and automatic laps, I'd like to mention this bug here.
My interval trainings have no automatic laps, but only manual laps. One training had two of 22 laps showing up, the other two had none of the laps showing up.
I'd be happy, if you could have a look into this - please let me know if I can assist by giving you further information/files/etc...