The police obviously believe the McCanns...that's what matters...not a bunch of armchair detectives
If you mean OG they probably didn't realise that Amy Tierney had to go from the night creche to 5A, by which time the shutter was closed, according to the McCanns. It was the first thing Gerry McCann did;
The deponent ran to the apartment accompanied by the rest of the group who, at the time, were seated at the table. When he arrived at the bedroom he first noticed that the door was completely open, the window was also open on one side, the external blinds almost fully raised, the curtains drawn back, MADELEINE'S bed was empty but the twins continued sleeping in their cribs. He clarifies that according to what KATE told him, that was the scene that she found when she entered the apartment.
----- Then he closed the external blinds
https://www.mccannpjfiles.co.uk/PJ/GERRY-MCCANN-10MAY.htmAccording to Fiona Payne she didn't go into 5A immediately, she spent ten minutes searching around the block. On her return she went into 5A, but Gerry left just before she did that, so it was just her and Kate then.
So how did Amy Tierney find both parents and a female friend in 5A before Gerry closed the shutters?