voltas/repeats not doing what I wanted

I have first and second ending on a passage. The measures 17-19 before the first ending I'll call the "common". This exact passage ought to play twice, eg, common, first ending, common, second ending, common, first ending, common, second ending and then moving on. However, MS4 plays 17-19 A FIFTH TIME before jumping over the voltas and moving on to 22. Measures under the voltas each have play count to 4 (setting to 5 as recommended in handbook doesn't change my problem. Nor does the value 3--it plays the same, hard to believe). The repeat list for the first volta is 1, 3, the repeat list for the second volta is 2,4.
PS
The handbook says nothing about "how" the hook-end of the volta will change playback, I need that paragraph written into the manual. Not seeming to matter experimentally. And why the recommendation for play count to be one higher than the number of times the ending is to play?