In the TSX ASCOM driver, uncheck the box to inhibit sync. Then the sync command will go through and the mount will center as usual. My MX+ does the same thing. I don't know why but if sync is inhibited, SGP will never get the target centered. Also, don't use the daily builds of TSX. They don't work with SGP at all, it won't center at all whether or not sync is inhibited.
For PHD2 to work, check off "enable tracking offsets" and "use DirectGuide" and "can get Pointing state". Also, I have had to use POTH between SGP, PHD2 and the TSX ASCOM driver. TSX doesn't seem to pass lat/long coordinates back to the other software which prevents some from slewing correctly. POTH has fields to manually enter your location coordinates.
Maybe this will help?
Chris