Reference footnote from an image caption?

I am trying to reference a footnote from an images caption. To reproduce:

  1. insert an image in your document
  2. add a caption to the image
  3. go to the end of the caption and try to insert a footnote/endnote
  4. nothing happens

There is no error message. But why is this not working? Is there a workaround?

Please have a look at

Bug 50711 - Unable to create footnote in image caption

(duplicate of fdo#48534).