Slitherine

I have seen the following sequence of events a couple times.

1) An army arrives in a region where there us some level of walls.
2) Next turn the army moves on to another regions.
3) Simultaneous with the move to another region, there is a message about having made a breach and inflicting some casualties... but mousing over the city, the walls are unbreached (still 2 of 2, or whatever) and the units in the city have no effectiveness or health loss.

So what is happening here? Is this working as designed? Is there really a breach? Are there casualties that I cannot see? Or does this mean that if they had remained in the region, this is what would have happened?

Breaches and damages are incurred at the very beginning on the turn, but as you moved away they repaired and healed during the same turn.