BG 4.5.1 SPOT/MOVE markers are placed regardless of line of sight to/from enemy units. To reflect the semi-simultaneous nature of movement the SPOT/MOVE marker is not removed until the next Spotting Phase if, at that time, there is no enemy combat unit in LOS (BG 4.1.5). Hope this helps. Cheers.
Roberto, perfect answer and thanks for quoting the rules reference.