Removing a word from a list seems to remove it from all schedules that list was included in, even if the word is also contained in other lists included in those schedules. This creates an inconsistent situation where a list can be included in a schedule, but (some of) its terms are not, and this seems to persist after removing and re-adding the list to the schedule. Personally, I would've expected a schedule to be the union of all the terms in its lists and any manually added terms; my best guess at explaining the observed behavior is that there is some sort of invisible per-schedule ignore list that gets populated when removing terms from a list included in the schedule.
To reproduce: create two lists A and B, add them both to the same (new) mastery schedule; open a dictionary entry for any word not already in the lists/schedule, add the word to both lists via the plus icon popup, then remove it from list A via the same popup. The word no longer appears in the schedule, despite still being in list B, and list B still being included in the schedule. Removing list B from the schedule and adding it again does not cause the word to appear in the schedule.
Advanced Search can detect this: you could select all words from list B and filter for "not in a schedule" (assuming you actually don't have the test words in another schedule); re-adding the affected words to the schedule using advanced search seems to work, but I would prefer not to have to do that regularly.
