Certainly there is a bug there, in fact two, and quite important ones.
This is how a group in safe mode behaves:
If they detect shooting nearby they switch to combat and will lie down holding position until they detect AN ENEMY causing the shots. Then they'll engange and when clear, they'll proceed with next waypoint. And doesnt matter the behaviour set in next waypoint, they'll never return to safe.
And now comes a funny test, add a blufor group with some waypoints (set SAFE in all of them), place the player near them, also blufor. When game starts, fire at the ground in front of the leader, all will lie down and will keep there forever trying to locate the enemy causing the shots, they'll not move.
Now repeat the test, but place an OPFOR soldier near them and at their back. The opfor soldier will fire, the blufor ones will return fire killing it AND this time the group will resume its waypoint plan, but in AWARE mode.