There are a number of kinds and grades of non-realism.

Well, obviously, once you know you didn't get a measurement, its probability becomes zero

has got to be one of the most embarrassing wrong turns in the history of science.

If you take all this literally, it becomes the consciousness-causes-collapse interpretation of quantum mechanics. These days, just about nobody will confess to actually believing in the consciousness-causes-collapse interpretation of quantum mechanics—

It's not an inevitable slide. An interpretation that is anti-realist about collapse, will not attribute the cause of collapse to consciousness, since it does not acknowledge the reality of collapse in the first place. It nonetheless has to explain the process of disregarding unobserved possibilities. ...which it can do by saying that the observer is updating their subjective map on the basis of fresh information. Selective anti-realism about collapse is a consistent position. Sweeping anti-realism,might not be, but that is another issue. The subjective interpretation of collapse is posited on information becoming available to an observer from an external world, so it is not sweeping anti realism.