I can’t speak for rfw7755, but as I have the same problem my answer might help you. I did not try the first one as I do not understand it. I did, however, test the 2nd one, which results in an error message because the program will then try to look up FirstName\ LastName which obviously does not exist.
So, escaping the whitespace does not work.
However, that was not necessary in the first place. using the UBT via command line works just fine when given the proper path of C:/Users/FirstName LastName/…/Project.uproject". It seems only the rightclick function does not work. I do, however, get the following warning which seems unrelated. I thought it was worth mentioning though.
So I can use this as a workaround for now.
