We are on ASA 9.12(4) and experiencing this same issue on one of our bookmarks. Internally, this site works across all browsers. When going through the SSL VPN, it only works in Internet Explorer.
In all other browser, it will get to the login page, but upon login, it will either reload back to login page or generates a 404. Internet explorer seems to be the only working browser. Enabling IE mode in Edge or IE Tab in Chrome does work, but the users experiencing this had IE removed from their corporate workstations and IE Tab is not free. The application that is experiencing this issue is Costpoint 8.
