Toro MX 5000. Cut issue

In heavy grass especially if a little wet my mower is leaving about a 2" strip of uncut grass between the center and right hand blades. In normal grass it cuts fine. The blades ARE SHARP. actually new. The old blades were also kept sharp and had the same issue. The deck IS LEVEL and the scalp wheels are adjusted according to the book. This is not a left to right uneven cut, this is a 2" strip of pretty much uncut or poorly cut grass in heavier grass. What else should I be looking at? Thanks

I have a recycle kit that I have since removed and it did not seem to make any difference. The origional blade were the ones sold with the recycle kit and the new blades are high lift Gators. I am now side discharging using the Gator blades and still having issues in the longer thick grass. If I go back over the 2" strip of poorly mowed grass it cuts it clean. Our lawn is very thick and I seem to only see this problem if the grass gets a little to tall and is a bit damp. Thanks