Nobody has responded, but I don't think Windows 10 or any recent RM update has anything to do with the situation you are describing. Rather, I think it's some awkwardness and confusion in the way RM supports adding spouses and adding marriage facts. The awkwardness and confusion can be hard to describe, but if you do the various add operations in certain orders they produce the results you wish and if you do the various add operations in certain other orders they do not produce the results you wish. If you do not get the results you expect, you probably are not really doing anything "wrong". You just have been caught in a trap that has been set by RM.
If you are adding a couple from Family View by clicking on blank spaces, the safest approach is to click on one of the blank spaces (say for the father) and add in minimal information for the father and cancel out of anything else it asks you to add. Second, click on the blank space for the mother and add in minimal information for the mother and cancel out of anything else it asks you to add. Only then, edit the father and mother separately and add all their additional information. For one or the other of them (it doesn't matter which one), add the marriage fact and select the other one as the spouse rather than clicking the add a spouse option.
The approach I just described is very conservative and will keep you out of trouble. I realize that in theory you can add a marriage fact and that you can add the spouse as a part of adding the marriage fact. In theory, this is easier than my more conservative approach and it ought not to get you into trouble with multiple spouses and that sort of thing. But sometimes it does.