If the creditor isn't willing to sign the paperwork to release the lien, the fact that they say it is paid is meaningless. A lawsuit to remove the lien will be both time consuming & expensive. I would continue to negotiate unless I was convinced that the parties holding the lien are acting in bad faith. Hope this perspective helps!
If the judgment was in fact paid the bank has an obligation to remove the lien. If the judgment was against you, you may be successful in contacting the judgment creditor yourself to seek documentation of its satisfaction.
Have an open conversation with your attorney regarding the efforts at removing. The attorney may be doing everything that (s)he can at this point.
Without more information, it's hard to comment. Your attorney may be having trouble communicating with the bank's attorney. They are the ones responsible for releasing the lien when the judgment is satisfied. Maybe you can get through to them.