The problem description is unclear about how the Media object path is stored. So isolating the problem is harder.
Please post a capture of the Media Object editors
Media Reference Editor opened from a Gallery tab showing the Shared Information
Media Object Editor opened from the Media category
Cllicking the Path folder icon button will show a dialog will the full path and whether the Relative Path was applied. (Note that 5.2.x and earlier will not validate a URL path imported from other software. You have to use Cancel, not OK to exit the dialog. Fixing a bad path is not possible in these versions. However, Gramps 6.0.0 and newer will allow URLs.)
