There aren't any known issues that would cause loss of histories. When I've seen this before it has been due to someone inadvertently working as an anonymous user and not realizing it, after which of course the work does not get tethered to their account.
Can you confirm you were logged in, and that if you go to "User" -> "Saved Histories" -> click on "Advanced Search" and show "all", that you don't see any extra histories there?
managed to find the lost histories by going to the cog button on the analysis page and then scrolling down to saved histories. For some reason these were available on the view all histories options.