For players to be added to the game in the AHL they either need to have played a regular season or playoff NHL game or ahve signed their PHPA agreement. Sometimes it takes a little while for players have sign these with their AHL teams.
They were previously in the game with their Euro league teams, but when they moved to play in the AHL then these new rules apply for legal reasons. There is usually a large dump of AHL players in an update once players start to sign.
Hope that clears it up.
