I have built my first TT bike a Cervelo P2sl and I am having a problem I have never encountered on my previous 4 road bike builds.

When I shift up on my front chain ring and I am in a middle gear on the rear cassette I chain will derail off the front. If I bring it in a bit by tightening the upper limit screw in any more than it is then it doesn't shift at all. So I am stuck between not shifting at all and unreliably shifting straight off the chain ring.

The front derailleur is parallel to the chainring and at the correct height so I am baffled. Has anyone seen anything similar or got any advice?