The Serco 1400 Border Skirmish mission seems to get skipped every now and then (maybe always but I don't check every day). The reminder mission for the next (2000) mission is available in it's place. This has happened to me more than a few times so it is repeatable.

Were you perhaps sitting in that station when the ad mission is scheduled to be removed and the real mission posted? If so, could you try redocking next time (or let me know if you already tried that)?

I've only encountered the missing mission for the 1400 Serco BS.

Didn't happen today, mission listed fine. I logged on five minutes before the hour turned and took the advertising mission this time though.

I will keep an eye out for this but I don't always logon at this time so reports may be sporadic.

22 March 0200 GMT Serco Border Skirmish mission was skipped. Logged on a few minutes after 0200 in-station at O-4 and the mission only listed the advertisement mission for 0600. Leaving the station and docking did not change the advertisement mission. Took the advertisement mission and completed it but it showed up in my mission list again.

I discovered another bug while checking this out, but, as I should have realized, what you've encountered isn't actually a bug. If the previous BS doesn't end within 2 hours of a scheduled time, that skirmish is skipped. It's call the "MinRegroupTime" in my code; maybe a discussion of its appropriate length should be had in the suggestions forum.