BoundleIdentifier missing from 19r1.1 to r2

after porting without any big problem several apps from 19r1.1 to r2, today I was stuck for three hours because, after building the app in r2, opening it I was getting a warning that the app had some problem (I can’t remember the specific wording).
Dropping the built into AppWrapper, I would get a warning that the app was missing its boundleIdentifier. Fine, at least I had a clue to follow.

Back to r2, I checked for it: it was there; I modified it into something else, changing also the name of the app, but the warnings both at opening and in AppWrapper remained.

To make a 3-hour story short: the problem eventually disappeared when I removed the file type group and commented the lines of code calling it.
Next move: Undoing the previous move, the original file type group reappeared and everything was again OK.

Hoping it may help somebody transitioning from r1.1 to r2…

[Edit]: the few times I was able to run the built in r2, the app looked as if Supports Hi-DPi was turned OFF.