I found a lot of issues moving between the touch screen movement and sending gcode in Repetier. I described it in this post. . Essentually, Relative Positioning movement is when the move is the amount from the current position (G0 X10 will move 10mm in the positive X axis). Absolute Positioning is when the move is to the exact coordinates specified in the move command ( G0 X10 will move to the absolute 10mm on the X axis). I found several times when I hit the down Z (1mm) on the screen and rather than moving down 1mm, the controller tried to send it to Absolute Z=1. Similarly, I would send a G0 Y0 in Repetier to send Y to home and nothing moved. Essentually because I used the touchscreen movement and it switched control to Relative Positioning which made my machine react as if the G0 Y0 command was telling it to move the Y by 0mm.
And FYI, you can force Absolute Positioning by first sending G90. And you can force Relative Positioning by sending G91.
If you don’t have the link, make sure you check out the Marlin gcode reference