I saw this once w/ CMBB v 1.0 with heavy arty. The FO had clear LOS (blue line). After seeing, the first dozen rounds go astray, I "walked" the targeting about 20 m (green line). After waiting another 2 min, the retargetted rounds went astray. It was way too late in the game to cancel the target and start anew so I let the arty fall. I found this behavior annoying but if this models the occasional real world F***ups, then ok. Unfortunately, I never saved the game. I have not seen this off-target shelling for a target w/clear LOS (blue targeting line) since this incident.
If I remember right, there was a thread describing this same behavior. I think BTS response was you have to cancel the arty mission and start anew. This really sucks when you have the big arty and loooonnnnng delays for a aquiring a "new" target. You really get penalized. Like I said above, if it models occasional real-world mistakes, then I guess I can live w/ it.