Slitherine

The light cav can charge from this position:



But when moved to the adjacent square, the tooltip declares that the initial facing was not within 45 degrees. No save, from an MP game.

The UI message is a bit confusing, but the actual rules are working as intended. In the second example your unit is making a free 45 degree turn, moving, then trying to make a charge that requires another 45 degree turn. That isn't permitted