I've just updated the block for sector 2.
It wasn't an interception within friendly territory, garrison C was erroneously placed by two flags...
Morale being... don't count flags after midnight... lol
At the same time I've now moved all garrisons for the block on sector 2, so that position A is untouched from the block for sector 5.
I've just finished one adventure, and for that particular block from G9 to sector 4 my generals marched off at the same time.
Despite that the fast general did not get intercepted.
So I fear your case is one where the second general has marched faster than the first one.
I also had one case where the first blocking general has reached the camp and disappeared,
but the fight never started and no smoke appeared. Thus the main general got intercepted and I lost soldiers again...
Lag, lag, lag... avoid doing blocks when it's laggy... but I can't... I need the blocks for the thrill...