Hi Pilou, in order to get a proper fill in Affinity the path needs to be one combined closed path.

If you select just the layer _faceCyan in your PDF, there are 4 separate unjoined paths that belong to that layer.

You will need to join those together before it will fill properly. If you just select the entire layer with open curves it won't get filled right, it's trying to fill each of the 4 pieces individually.

You can join the curves in Affinity Designer by selecting them all:



Go to the "Node" tool:



Choose the "Join curves" Action here:



Now with it being one single path instead of 4 separate sub paths you can fill it like you wanted:



When the 4 pieces are separate then applying a fill goes like this instead:


- Michael