According to today's Raw SATCAT Data from Celestrak, the launch designated 2018-099 (SpaceX, December 2018) still has twelve unidentified payload objects!
Objects D, J, P, T, U, W, X, AV, BA, BD, BE, BS
Object BS even has it's own question: What is “OBJECT BS”? because it lagged behind all of the other objects without any even approximate orbital elements in the satcat.
Almost five months after the launch, how can there still be twelve unidentified payload objects?
I've been watching this as a favor to the asker of Where can I find the TLE of ExseedSat 1, India's first ever private LEO satellite? which may or may not be one of the twelve.
update: Of the twelve objects listed above, the following four have only recently been identified. The rest are still a mystery.
J: SPAWAR-CAL-O U: SPAWAR-CAL-R W: SPAWAR-CAL-OR BD: CENTAURI-1