selwyn This sounds like bug.
However, when you rotate image, all old faces get deleted, and this is intended behaviour, not a bug. Program will then find and recognize faces anew. Face recogtion is very depenable on image orientation that is why there is no point in keeping old recognition data.
Let us try to figure out is this issue with rotation or just diplaying results of this rotation. If you leave image view mode after rotation, will thumbnail be rotated or will it remain not rotated too?
Then? can you please re-index image using context menu? Will it be rotated after that?