When I use analog pitching why is the bar moving after I start the pitch?

[el FIama BIanca_XBL]

When I am using analog pitching and from the stretch the stop bar will be in one spot then When I start the pitch delivery it will move higher up. It happens a lot....

[ArGenTin32_XBL]

Does your left trigger get stuck? When you hold down the left trigger it quick pitches. This is what you are seeing with the line moving. My left trigger acts up sometimes and it does the same thing to me too.