Map Editor - Exclude From Countries Bugged

Expected Behavior:
When units are set to be excluded from certain countries they will in fact be excluded from those countries.

Actual Behavior:
When editing a map of mine and adding in new unit types, I ran into some issue where setting units to be excluded from specific countries made them become only availible in those countries.

Steps To Reproduce The Behavior:
I've gone back into the editor and tried, actually, to NOT reproduce the behavior. But it seems to be persistent. Additionally, units from the same map that were properly excluded from specific countries are now - in game - availible to all countries including the ones they're listed as excluded from.

For example, in my 1800's scenario, the French are supposed to be able to produce an advanced form of Cavalry, and thus the default Cavalry unit is excluded from the French 'countries.' This has worked just fine in my game for years. But after today, when trying to exclude some new units from specific countries, the Cavalry (which were not even touched) thereafter became availible to French 'countries' as well despite being excluded from them on the unit's info sheet. And I can't seem to be able to undo that.

Information:
Map Editor through the browser.