This problem has started for me today for the first time. There was a Firefox update shortly before but that might be coincidence. When I start entering an email address for sending, the possibilities ( with e.g. name(s) and email address(es)) appear in a box drawn presumably from Contacts, But when I click on the right choice the details disappear leaving a red box with the letters I have typed and an x for deletion. That is the same result as if you type in letters for a contact which does not exist.
I have checked Settings and the box for auto-filling contacts is ticked. I am using a Windows(11) laptop.
If I compose an email using on my wife's Ipad I the auto-filling works fine.
Much appreciate any help in solving this.
