I can think of many things more plausible. Not every loose end gets neatly tied off.
Simplest is a malfunction in the jump drive, nobody really knows what happens because a miss-jump has too many unknown variables. In a tight formation, it might even influence several jumpships to arrive together at the same wrong destination. If they are lucky.
More likely and more plausible, they were spirited away by any number of secret factions that never reveal all their hidden assets. Choose your flavor of the month.
Again, they might have just refused to participate one more tine in the great insanity known as the Inner Sphere. After choosing a world marked as no longer viable on the Map, they absconded to establish a more cat friendly peacetech sort of place.
Well, it could happen ...
GC