Did your units attack from a tile next to the river or did you move them one or more tiles before attacking across the river?
The 2nd case is still bugged, because the river crossing is not taken into account, thus the combat odds are lower than displayed.
Hmmm, I think they were both cases, but I see your point.
I wonder what would have happened if a road CAUSED my unit to cross the river. That bit about units taking roads vs. directly attacking a unit in the next tile drives me crazy.
It just may have been coincidence that all four of those battle losses involved crossing rivers with 99.9% combat odds.