My guess it's either too old or a Mesa update broke it. There was a user who was using Linux Mint a month or two ago who had this exact issue, which started after Mesa got recently updated. After fiddling with it in multiple ways they ended up installing Debian instead where it worked again. Rolling distros with the latest Mesa also didn't have the issue either.
I believe the theory regarding it was Mesa dropped support for some older Intel iGPUs which then broke it completely in the Mesa update. It was never confirmed or anything though, so it's probably not right.
sinad, posting as much information about your system (what version Linux Mint, what CPU, what GPU or if it's using an iGPU, etc.) would likely help a lot too.