Actually, you have to tap select and mark the folder then open. If you want to save it on your current folder, you must go up one level then mark that folder.
This is somehow Apple's iOS problem, not Affinity problem.
== But, below is my problem on Affinity Designer ==
Even after I put the export destination, Affinity keeps on saying this after you execute that export button and place it on a folder, but it is awful forever and you decided to tap that export button again:
items are being exported to your chosen folder.
I want to ask
IS IT ACTUALLY WORKING?
When I export from the document menu (I don't know the name, I only knew the paper with three dots icon. It is definitely not the export persona) then export, it is fine. File exported easily, but with less options than in the export persona.
Someone give me some enlightment.