Quantum Weirdness No More

 If a light splitter and combiner introduce a $90^o$ phase difference in the output beam(s),

In the last two 'blocked' cases, beams at $0^o$ and $180^o$, and beams at $90^o$ and $270^o$ do not interfere and cancel as they are on spilt paths.  Beams at $180^o$ and $270^o$ phases are visible beyond the outputs of the splitter.  These outputs are at opposite phase to the other outputs of the splitter, but do not interfere and cancel with them because they are on different paths.

Not weird.