This morning the correct skin is showing for me too.
When I saw a p51 res file loaded, I went to the hanger and saw a list pick for the 20FG; but selecting it produced the 339FG skin. Picking a different skin, even a different plane, and coming back to this skin did not fix the problem. The only proof that the top picture was taken on-line is TALAS and Waffle being listed in the upper right corner. The bottom picture was taken off-line to show what the skin was supposed to look like.
I'm running 256-skin resolution. Maybe this new 20FG skin was taking over the skin slot (like p51d3) that was previously filled by the 339th skin, and it takes a game restart to propagate the skin through the different skin resolutions.
MachNix