Stupidity is the problem. We have a moron in the White House who has no understanding of reality or diplomacy. The bill in question had a safety clause included. The clause states that the official embassy move could be delayed for six months at the decision of the president:
The bill became law after Clinton declined to sign it for a 10-day period while Congress was in session. He, George W. Bush and Barack Obama all postponed the embassy move every six months for each of the 22 years since the law was enacted.
The passage of the bill was unfortunate as it indicated US ignorance of and complete disregard for all the parties concerned. The delay passage was added to ensure that something stupid was not done. Trump just blew that. This is probably the most significant of his complete string of disasters.