Secure Form is blocked

I regularly receive email advice (via Thunderbird) from companies to access my account with them. Two days ago I selected a link to direct me to the secure form. I note that the exact same link has been provided to me in the past and opened. This time however I was confronted with "Invalid Address". I was advised to copy the link into another browser; I chose "Edge" and the form opened. I have cleared FireFox's "Recent History" but that still gives no joy. How do I overcome this? Is there something in a configuration file that I might edit, or a potentially corrupt Windows Registry entry? I do not use any Windows Security depending upon Bitdefender (which has never created any issues of this nature).