This will be a long answer (relatively). There are three possible responses:
1. You can file suit to get the lien invalidated. This is a Circuit Court action in which you would present any defenses to the lien (improper filing, not valid because GC has been paid, etc.) and depending on the defenses can take as long and be as expensive as a suit to enforce.
2. You can place a bond or cash collateral with the Court and have the lien released that way. While this ties up some cash, it is the quickest way to get a lien released. You would then see if the GC sues to enforce its rights against that collateral. If the GC did so, you would present the same defenses that you could have presented in Option 1.
3. These first two involve attorneys and lawsuits in Circuit Court. The third option is to simply wait 6 months and see if the GC sues to enforce the lien. If you do not plan to refinance or sell the property in that timeframe, the lien will sit there and will become dead letter after 6 months.