Continuous endnote numbering in non-concatenated text frames (legends)

Hey!

I have a document with a long continuous text that contains endnote references. Some of the endnote references are also contained in image and diagram legends. These text frames are not linked to the text frame of the continuous text. Now I have the problem that the numbering in the separate text fields (picture and diagram legends) get any numbers (see screenshot 1). When I place the endnote in the continuous text, it has the correct number (see screenshot 2). How can I solve this problem?

Thanks for your help.

Belinda