When I tried using a Guest-account*, oddly, in the mylist the checkboxes in front of files and the "action"-drop-down were shown. When I then tried selecting some files and submitting a "remove from mylist", "mark seen" or "mark unseen" I luckily encountered the "Internal Server Error"...
I guess you already included the right permission-checks, so it's hopefully moreless an optical issue that these checkboxes and the drop-down are shown when using a guest-account.
*) Other browser without the login-cookie of course
mylist edit actions shown to guests [FIXED]
Moderator: AniDB