I've been having an issue lately that I didn't have originally, where a small section at the rear center is printing super thin, or not at all. It's like the base plate isn't even, but no amount of manual or auto leveling seems to help. Here is an example with the calibration print, but it's the same for all prints. It seems to be just a semicircle in that area. Has any anyone experienced this or know what is causing it?