Could be a pack of wild coyotes in the area, that might be stifling the toms or jakes from gobbling. That turkey you saw running away was probably spooked by something --- probably you --- so he might have came in silent before he saw you. May I suggest setting up in the morning...between his strut zone and roost. Just after dawn...just do some soft tree yelps --- loud enough for the tom to hear you. Once he acknowledges you --- shut down the calling till he flies down from his roost; or if you see one of his hens fly down. Then you can perform your hen fly-down cackle (along with wing beats, by flapping your hat on you're thigh) from a roost followed by some yelps.

The tom might service one of his hens early in the morning, finish, and quickly come to you while it's still early. Do a cackle run, followed by a few yelps...which means in turkey language: Demand the tom too come to you immediately, so that she can be serviced right away. The sound limit range for a gobble (in the right conditions) is about one mile. If you can find some higher elevations above the swamp...it might be a good roost location for a tom, because he can sound-off louder and his gobble will travel further.

Good luck next spring...

Erno