It's a well documented issue. Maybe your headphones and/or ears just aren't sensitive enough to notice the issue. Plenty of people don't see the difference between flac and 240p youtube uploads, after all.
Hmm, did you make the 240p vs FLAC strawman deliberately? Or is the bug (as you're able to reproduce it) really that bad? I know OP was using high-end headphones but I expected at least a slight hissle.
(My attempts to reproduce were with a PX80, S2PGFY-003, JBL Pulse and Bose Companion 50. I included the speakers because I couldn't get the headphones to do the trick)
