Hi!
It’s probably that, altough I’m pretty sure it should return the correct picture, as it’s parsed with an internal wordpress call.
I gladly put together a snippet to fix that, but I need to know how the mapping is done. From what I can see, this might be the solution to put in the functions.php file:
This should recognize the double slash pattern and try to replace that with the correct home url. Let’s hope it will work.