I am completely as a loss here and this whole thing is about to drive me insane.
I have been trying to update the mod I am working on for the new release of Last Chieftains, but the game is interacting in seemingly impossible ways.
When I try to run the mod after updating it, everything works except for the tech trees, which remain with their original civs, even when I override those civilization tech trees with the custom ones.
When I fully delete the data set from the mod, the game still uses the custom units that only exist in that specific data set. So it pulls units from a data set in a location that does not exist, and it manages to use them as if it does.
After they released a new DLC, the mod tech tree no longer works. For now, to have your custom tech tree, you have to replace the original files.
As for your custom units working without your .dat file, it’s probably because you removed the mod while the game was open; (when you open the game, it temporarily saves registered or local mods in RAM); I don’t know in what other situations this might happen, as it has never happened to me before.
The tech tree ui is not the issue; that works fine. The issue is the tech tree in AGE itself. The game doesn’t acknowledge it, even with the generic civilizations in the mod file. It acknowledges the units, the techs, the effects, and even the modded attributes, but not the tech trees or team bonuses.