2005 Kubota M5700 hydraulic issue

[P.o.b. Ranch]

I have a 2005 Kubota M5700 tractor with a hydraulic shuttle. When I put the shuttle in neutral it emits a squeal like it is starving for fluid. I checked the level it is full. Just did complete 600 hour service 30 hours ago. Has all new fluid and filters. Doesn’t make the noise when in forward or reverse, just in neutral. Any ideas would be greatly appreciated.