Sigh... it unfixed itself. Back to 2-hour turns.
Now, not being one to give up easily and following Migi's advice, I found the following fleet history entries from recent turns that look decidedly fishy:
43 23300 Asteroid #70: Move to Location 2121525110.0
43 23300 Asteroid #70: Move to Location 2121532310.0
43 23300 Asteroid #70: Move to Location 2121539510.0
[repeated many more times]
43 23333 JP3: Tomten (JG): Standard Transit 2121525110.0
43 23333 JP2: System #53 (JG): Standard Transit 2121532310.0
43 23333 JP3: Tomten (JG): Standard Transit 2121539510.0
43 23333 JP2: System #53 (JG): Standard Transit 2121546710.0
43 23333 JP3: Tomten (JG): Standard Transit 2121553910.0
43 23333 JP2: System #53 (JG): Standard Transit 2121561110.0
43 23333 JP3: Tomten (JG): Standard Transit 2121568310.0
43 23333 JP2: System #53 (JG): Standard Transit 2121575510.0
[repeated many more times]
43 26979 Amity-A I: Move to Location 2122237910.0
43 26979 Amity-A I: Move to Location 2122245110.0
43 26979 Amity-A I: Move to Location 2122252310.0
43 26996 Acute-A VI: Move to Location 2122396310.0
43 26999 Acute-A VI: Move to Location 2122396310.0
43 27002 Acute-A VI: Move to Location 2122396310.0
[repeated many more times]
43 23883 Armendáriz Resources Limited: Refuel from Colony 2122072310.0
43 23883 Armendáriz Resources Limited: Refuel from Colony 2122086710.0
43 23883 Armendáriz Resources Limited: Refuel from Colony 2122101110.0
[repeated many more times]
43 24176 Asteroid #284: Refuel from Colony 2121532310.0
43 24176 Asteroid #284: Refuel from Colony 2121546710.0
43 24176 Asteroid #284: Refuel from Colony 2121561110.0
43 24176 Asteroid #284: Refuel from Colony 2121575510.0
43 24176 Asteroid #284: Refuel from Colony 2121589910.0
[repeated many more times]
43 24222 Fantomen-A II - Moon 1: Refuel from Colony 2122201910.0
43 24222 Fantomen-A II - Moon 1: Refuel from Colony 2122216310.0
43 24222 Fantomen-A II - Moon 1: Refuel from Colony 2122230710.0
43 24222 Fantomen-A II - Moon 1: Refuel from Colony 2122245110.0
[repeated many more times]
43 24435 JP4: Allentown (JG): Standard Transit 2122129910.0
43 24435 JP1: Albuquerque (JG): Standard Transit 2122137110.0
43 24435 JP4: Allentown (JG): Standard Transit 2122151510.0
43 24435 JP1: Albuquerque (JG): Standard Transit 2122165910.0
43 24435 JP4: Allentown (JG): Standard Transit 2122180310.0
43 24435 JP1: Albuquerque (JG): Standard Transit 2122194710.0
43 24435 JP4: Allentown (JG): Standard Transit 2122209110.0
[This one is pretty bad and #1 on my to-hit list]
43 25107 Semarang Prime: Refuel and Resupply from Colony 2121964310.0
43 25107 Semarang Prime: Refuel and Resupply from Colony 2122396310.0
[repeated many more times]
43 25359 JP1: Albuquerque (JG): Standard Transit 2121525110.0
43 25359 JP3: Annapolis (JG): Standard Transit 2121532310.0
43 25359 JP1: Albuquerque (JG): Standard Transit 2121539510.0
43 25359 JP3: Annapolis (JG): Standard Transit 2121546710.0
43 25359 JP1: Albuquerque (JG): Standard Transit 2121553910.0
43 25359 JP3: Annapolis (JG): Standard Transit 2121561110.0
[very, very often]
43 26298 Ag Mines Corporation: Refuel from Colony 2121820310.0
43 26298 Ag Mines Corporation: Refuel from Colony 2121834710.0
43 26298 Ag Mines Corporation: Refuel from Colony 2121849110.0
[repeated many more times]
43 27662 Annaj Prime: Refuel and Resupply from Colony 2121532310.0
43 27662 Annaj Prime: Refuel and Resupply from Colony 2121546710.0
43 27662 Annaj Prime: Refuel and Resupply from Colony 2121561110.0
These are SQL-pulled from the last 383 increments, all 2-hour (7200 sec) turns. Now, which fleet is the culprit? I notice that e.g. the last bunch (Annaj Prime: Refuel and Resupply from Colony) does not have 7200 sec between entries, but why is the fleet repeating this order? Does any of this look legitimate?
I could delete or move all fleets that seem suspicious but I'd prefer minimally invasive surgery on the DB. Some advice would be welcome!
While we're at it: is it enough to change the current x-coordinate to move a fleet?