How to unscrew the spinning bolt

Hi, I’ve recently noticed that the front suspension on my Trek Marlin 5 has become a bit squeaky, so I decided to give it a proper clean. After watching a few videos, it seemed like a fairly straightforward job but I ran into an issue right at the start. One of the bottom bolts on the front fork just spins in place and won’t unscrew. I can turn it easily, but it doesn’t come out. Any advice on how to deal with this? Thanks!