Sync to 2nd device only shows recent Steps ?

I downloaded To Do on my iPhone and imported my lists from Wunderlist.  A few days later, I installed To Do on my Mac and was able to see all of the lists and steps that had been imported previously.  So far, so good.

I have a number of lists with sub-items/steps that I keep as packing lists for various situations.  I don't check off the sub-items/steps, I just change their text (from 1x to 0x, e.g.) and move them up/down within the step list as required.  I edited one of these lists on the Mac, but when I checked my iPhone, the list only showed the steps that had actually been edited/moved.  On my Mac, I see List A, 0 of 17, but on my iPhone (after verifying that the sync was up-to-date), I see List A, 0 of 6.  Why are the remaining steps no longer syncing correctly?