Time limit to cash in completed missions?

Anyone know if there's a time limit to cash in missions. Did some morally questionable kill civilians missions and became hostile with faction controlling the system I wanted to cash them in at so had to run away and become neutral again. With my irl time constraints this took about 7 days and the mission have now disappeared from my transactions tab. Just part of the game or something I should pester FD politely about? Worth about 1.5 million in total for the three missions.

Cheers
 
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