You can put your drain anywhere in the shower...most people try to get it closer to the center when using a clamping drain, and there are more options when using a linear drain. John is putting words in my mouth...just to be a pain and to try to instill doubt in anything I say - such a professional! The key is you need to maintain a MINIMUM of 1/4" per foot slope to that drain, regardless of where it is. If it isn't centered, that will often mean that the slope from one wall will tend to be steeper than the slope from the others - IOW, it will have to be steeper than that 1/4"/foot OR, you will not have a level perimeter, that most people like. Using a linear or trench drain, you will have sloped wall/floor lines on at least a couple walls. Say you have a 6' wide shower...the round clamping drain is 1' from one end...that means it is 5' from the further wall, or a minimum of 1.25" drop from that wall to the drain (actually more to account for the hypotenuse of the triangle into the corner...that will be more than 5'). If you want the perimeter level, that means that in the one foot to the other wall, it would have to have 1.25"/foot, or 5x steeper! Having a level perimeter is an aesthetic thing, not a physical requirement. There are limits to where you can put the drain and have it both look good and perform well. SO much for John's assertion that you can put it anywhere!
While what you are seeing happens (putting in a liner, testing it for the inspector, then tearing it out and essentially starting over), at a minimum, once the new liner and drain is installed, you need to do another flood test to verify what was done was done properly. MOst plumbers (not all) wont' do a mudbed to put in a preslope. Most contractors don't want to schedule the plumber in twice - once to install the drain and later to install the liner after the preslope has been installed, with the tiling guy in there in before and after. If they are going to move the drain, that could affect the slope of the drain lines, the depth of the trap, how well the vent line works. All of the things that were tested during the inspection, now changed.
Technically, the liner is the waterproof layer, and code requires it to be sloped to the drain. An inspector SHOULD NOT approve a shower install without that layer sloped, but it happens. They wouldn't approve the drain pipe being run with no slope...they should not approve the liner with none, either. Tearing out what was inspected and approved happens, but it's got its potential problems, both with compliance and ultimate success. Good luck. IT may all work great when done. The inspector is not really your enemy.