Firstly, the game has restarted so you can't check these anymore.
Secondly, you most likely didn't lease the CRJ. This could happen for example when you press the lease button, and after that confirm, but when some1 else has leased the plane while you have been trying to lease it. However, if this is the case, you should get a notice of it after pressing 'Confirm lease'.
And thirdly, the ATR's are usually very popular, thus people may lease/buy them very quickly. If planes disappear from the list, it is either because the lessor decided not to lease it (usually the player), the lessor (computer) scrabbed the plane, or some1 bought/leased it. Nothing weird there