There seem to be a recent customer relation policy that I first experienced just before COVID with one of the airlines I use as Pax the most : Lufthansa ; as soon a something goes wrong . like large delays, no bags on carrousel, excessive queues at security, etc.. , the airline ground staff disappear and Pax are left alone, Swiss belonging to Luft, might be the same policy applies. The argument being for their staff not to face angry mob , understandable, but it does not help building a good relation with their customers either. .
Knowing the bags were not on board ( can happen as explained before) but not telling the Pax and have them waiting 2 hours in front of an empty carrousel is really not acceptable and is not going to help them getting more customers for sure.