Can't Fly in The Peaks Map despite done everything

[Enkidoh]

Have you though? If the list is saying you're still missing one, then you probably are (I'm not discounting it's a bug, but more often than not, it's really just a current that has been overlooked).

In the Peaks, use your aether compass to see if it detects anything, and check here to look for the quests that unlock the aether currents in that Region (some aether currents are rewarded by optional sidequests, and some are rewards for completing certain main scenario quests). That link also lists the locations of all the aether currents in that area.