Why doesn't our new apartment sink drain after the first day?
It is possible that the plumber installed a "balloon" in the drain line, in order to perform pressure testing.  The plumber is supposed to remove the balloon after the pressure test is accepted.  On rare occasions, the plumber forgets to remove the balloon.

The plumbers hired by my homebuilder made this mistake.  It took days or weeks for the balloon in our drain line to cause the sink to stop working.  During this time, we had increasing amounts of gurgling, cross-talk between sinks, and slowing down of drain times.  A competent, third-party plumber we hired was unable to find the problem.  The builder failed to identify the problem on their first visit(s).  Both the builder and the third-party plumber guessed (incorrectly) that relocating and/or replacing a "Studor valve" might fix the symptoms.  Eventually, the builder's punch-list/final clean-up guy identified the real problem, but only because the balloon was located in a cleanout whose trim work was done improperly.

Studor is a brand of air-admittance valve, or AAV.  These valves are used in some jurisdictions when it would be inconvenient to vent a plumbing fixture through the building's common plumbing vent stack.