Dorico 3.5 articulation change problem

I am attempting to set up an expression map for Audiobro’s brass library. When I assign a flutter tongue articulation to a note, I can’t get any other articulation to take afterwards. I have attached a sample file. For reference, the string staff works correctly.
brass (357 KB)

Have you tried unchecking the ‘Auto’ option in the Mutual Exclusion Groups section of the Expression Maps dialog and adding your flutter-tongue articulation to the same mutual exclusion group as the other techniques?