I-Firefox Isithangami Sokwesekwa

Hi there, I have a strange behavior in firefox: when navigating to Yeastar support website (https://support.yeastar.com/hc/en-us) and trying to sign in, i receive the following message: "To continue signing in using Firefox, allow cookies to be stored on this device. You might see this screen more than once. " If I put my username and passwords, I am unable to press the "Sign in" button. If I do the same from an incognito session, the message doesn't appear and I am able to log in through the "Sign in" button (see attached screenshot).

I tried to read many articles about allowing cookies from the firefox documentation but none has solved my problem. I'm running Firefox version 91.0 from a VDI (Citrix Desktop) and I have no admin privileges. Is there anything I can set in order to resolve this problem?

Under about:preferences#privacy there is a section 'Cookies and Site Data'. I have my settings set to CUSTOM and block all cookies. I then have managed my exceptions. I did a refresh resently, all that was lost. The best I can do currently is to have wordpad open and manually type each line out in my exceptions and then if needed in the future, I could copy and paste. There might be a better way that I do not know. I do know by default, the 'Managed Exceptions' under 'Cookies and Site Data' does not save if 'Refreshed'. Please address a better process and not my choice on blocking all cookies, thank you.