It is a problem with the TK's stock MiG-23MF.
TK set the ApexWeaponstations with the SpecificStationCode=AA-7, but forgot in the weapondata.ini to designate the station code AA-7 to the Apex missile. So the game engine does not find a missile which can loaded on the ApexWeaponStations. To solve this you can either edit the weapondata.ini with weaponeditor and put the station code into the AA-7A - AA-7D or you edit the MiG-23MF.data and make it as the lines show below:
[LeftApexStation]
SystemType=WEAPON_STATION
StationID=6
StationGroupID=1
StationType=EXTERNAL
AttachmentPosition=-1.47,0.24,0.00
AttachmentAngles=0.0,0.0,0.0
LoadLimit=500.0
DiameterLimit=0.20
AllowedWeaponClass=IRM,SAHM
AttachmentType=SOVIET,WP
ModelNodeName=shoulder_pylon_L_2
PylonMass=100
PylonDragArea=0.03
//SpecificStationCode=AA-7 <<<<<<<<<<<<<<<<<<<<<<<<<<<THIS IS THE LINE
[RightApexStation]
SystemType=WEAPON_STATION
StationID=7
StationGroupID=1
StationType=EXTERNAL
AttachmentPosition=1.47,0.24,0.00
AttachmentAngles=0.0,0.0,0.0
LoadLimit=500.0
DiameterLimit=0.20
AllowedWeaponClass=IRM,SAHM
AttachmentType=SOVIET,WP
ModelNodeName=shoulder_pylon_R_2
PylonMass=100
PylonDragArea=0.03
//SpecificStationCode=AA-7 <<<<<<<<<<<<<<<<<<THIS IS THE LINE