A recent change in the DAX language transformed the behavior of IF statement, so that it should not return BLANK but only TRUE/FALSE if the results should be logical expressions. In that case, the BLANK is transformed in a FALSE condition.
For example, consider that the result of the following expression is FALSE and not BLANK:
IF ( 1 = 1, BLANK(), TRUE )
I wrote a longer explanation of that, thanks to Jeffrey Wang who provided the details of the implementation. Also a big thanks to Darren Gosbell, who raised the initial question.