Hi Krileon,
After the recent encounter with drop down fields, I think the bug for conditional is specifically in multiselect dropdown. Hope you guys can fix it soon.
It works for checkboxes, it also works for Drop Down Single Select. But it does not work for Drop Down Multi Select. Please test at your end using Dropdown MULTI select and see if the optional field appears immediately when the conditions are met at the front end profile edit mode. Hope to hear from you soon. Thanks
(Btw, forge area seems to be having some problem because i couldn't reply the post)