I've noticed this as well. Previously, tracking would indicate when a parcel was received by U.S. customs. There was almost always a 4 business day delay between the date a package arrived at customs and the date it entered the USPS. My guess is that people were complaining to customs about the delays and customs reaponded by entirely removing their handling dates from tracking. That's only a guess. Personally, I didn't think 4 business days was too bad given the likely volume U.S. Customs handles.
I kind of miss the "ISC" and occasional "Inbound into Customs" scans. At least you knew your coin made it to the right side of the Atlantic! Maybe things will return to normal after the Holidays.