Vanishing AI in flight (FS2004)

I did a check on this forum before posting and found a related message that didn't seem to be resolved, so thought to ask again. I just finished creating a large number of flightplans with aircraft mostly intended for AI (WOAI, MAIW) but with some flyable ones that couldn't be found in AI versions thrown in. Anyhow, turns out that most of the AI aircraft disappear after having departed, say within about 5 miles or so of the airport. They just cease to exist. I've observed this at several airports and watching different types depart. Among the ones that are creating a problem are the MAIW & WOAI airliners, although using modified flight plans, but no errors have come up with regard to schedule times being overlapping or anything like that, and the AFCADs have ample parking of the proper type and are error-free. Before this AI project was completed, I recall having been able to watch aircraft departing/arriving from the maximum range of the F-16 radar gauge (e.g., about 30 mi). If anyone has any ideas I would be happy to hear them, as it seems a waste to have all these planes installed but only able to see them on the ground/while taxiing (chasing them is half the fun).