This may all be information you know and have tried, but to be clear, when you say you are training tactics, you do mean "Tactics Only" under Match Training, right? Not Tactics under Main Focus?
I find the best way to get tactical familiarity up is to set the Scheduling slider all the way to the left, maxing out "More Match Training," and of course keeping Match Training set to Tactics Only. My squad will usually master all three tactics around the late 2nd / early 3rd month of the season, though I'll turn down Scheduling a notch once they're about 80% familiar with the tactics.