On the page https://office.akado.ru/user/login.xml it's not possible to store or get requisites

On the page https://office.akado.ru/user/login.xml it’s not possible to store or get requisites. Kee just doesn’t react on this page.
I get error in Browser Inspector when I tried to find page related passwords manually. My point, that this is the only one page that I met with such problem while usage of Kee extension, and content-type of that page is xml, so my idea, that somehow, this is the reason why Kee doesn’t work on that page.
I made video with ScreenToGif and saved it as .gif. In that video, you will see that type of page is text/xml and not text/html, which can be the reason (from my point), this page ends with .xml extension (which of course doesn’t really matters). Also you will see, that after manual retry to find requisites to site, some error happens in Browsers Web Inspector (not web page developer console).
This page is the page of my internet provider, so I’m not sure that I’m able to share requisites from it.
I tried to create requisites record manually through Kee. Also I tried to compare and to change KPRPC JSON record in KeePass Password Manager 2.38 after comparing with working requisites which successfully loaded on other sites, and it has no result. Version of Kee is 3.9.5. Version of Firefox 89.0b15 (64-bit)

Error stack: can't access property "framePorts", window.kee.tabStates.get(...) is undefined background.js:1 init moz-extension://cd66e759-2179-476d-8c55-0ae26205d440/background/background.js:1 apply self-hosted:2735 applySafeWithoutClone resource://gre/modules/ExtensionCommon.jsm:621 applySafe resource://gre/modules/ExtensionCommon.jsm:604 sync resource://gre/modules/ExtensionCommon.jsm:2413 listener chrome://browser/content/child/ext-menus.js:275 withHandlingUserInput resource://gre/modules/ExtensionCommon.jsm:119 listener chrome://browser/content/child/ext-menus.js:274 apply self-hosted:2735 applySafeWithoutClone resource://gre/modules/ExtensionCommon.jsm:621 fire resource://gre/modules/ExtensionChild.jsm:806 recvRunListener resource://gre/modules/ExtensionChild.jsm:810 recvRunListener self-hosted:1178 _recv resource://gre/modules/ConduitsChild.jsm:78 receiveMessage resource://gre/modules/ConduitsChild.jsm:184

Best regards,