As I've got such a problem as looping password request from Deluge plug-in (blocking access to webUI) and can't find "coding" solution, as my RPi 3b+ OMV system running over BerryBoot (and I'm noob in Linux yet O_o). Most of all I'm using MacBook for access.
It seems weird, but if you'll use Google Chrome- everything works flawlessly. As from MacBook, I've tried Safari, Firefox, Chromium (over Parallels on Debian 9)- no chance. IE from Win10 works fine. Chrome and Opera from Android works fine.
Hope it will help someone, as there is no info on this across web.