OK, seems like the problem is much bigger.
Once again I‘ve found an invisible harvesting mission (using space on the worldmap), but this time it‘s located in Africa.
I‘ve also send a Firebird to investigate the questionable location, but it was unable to detect anything.
To me it seems like some harvesting-missions are just not displayed, also the usual notification on the left upper corner of the screen didn't appear. Of course there have already been some harvesting-mission witch didn’t cause any problems (The notification appeared and the corresponding symbol was displayed on the worldmap).
Currently I really got no clue whether this hidden missions are intended or not.
Once again I‘ve attached the corresponding savegame.
Regards, Magniff