I'm puzzled. I don't think the Primary/Master password should be affected by the OS.

Are you running the same Firefox program file and launching the same Firefox profile in both cases?

Or did you copy over some files from your Windows 7 partition to set up the Windows 10 partition? Saved logins require a pair of files (lock and key): logins.json and key4.db. You could try migrating those from your working Windows 7 profile to your non-working Windows 10 profile again.

Note that each profile has their own Primary Password stored in key4.db in the profile folder. You need a matching logins.json and key4.db pair to be able to access the passwords in Lockwise.

I'm puzzled. I don't think the Primary/Master password should be affected by the OS. Are you running the same Firefox program file and launching the same Firefox profile in both cases? Or did you copy over some files from your Windows 7 partition to set up the Windows 10 partition? Saved logins require a pair of files (lock and key): logins.json and key4.db. You could try migrating those from your working Windows 7 profile to your non-working Windows 10 profile again.

I agree - my Firefox master password should work on either OS as they are separate OS's, drives AND Firefox installations. I haven't altered any of the file on either OS. I hadn't used Firefox using W10 in awhile but when I tried & input the same password that works using Firefox on W7 the password box "blinks" & clears the password - no error message or anything to retrieve the password. It used to work using W10 - I only have the one Firefox acct so presumably it wouldn't allow 2 different passwords(?).

It used to work using W10 - I only have the one Firefox acct so presumably it wouldn't allow 2 different passwords(?).

Every Firefox profile can have its own Primary/Master password set, or none set. It is purely local and does not sync.