Having owned both the original PMI Trracer and the Empire Trracer, I've run into this common problem over the years. While super reliable, the weak spot on the Trracer is the cup seal. I've noticed that even the smallest nick will cause the marker to leak air. Replace your seal with a new one and it'll be fixed (especially since flipping it reduced your problem).
My old Trracer eats through cup seals like there's no tomorrow, I've noticed that CO2 will reduce the lifespan of the seals. Giving it a good coat of oil helps with the issue a bit.