nanoDLP

Hi all, new to DLP but machine is coming along. I'm having trouble with z movements, raspberry pi 2, ramps board, muve3d marlin, nanodlp 1322. I'm able to move the z axis through the terminal window and calibration screen so I don't believe it to be a hardware gremlin rather it seems that no z movements are being generated during the plate process. I did come across some log file info that looks interesting:

2016/12/31 17:17:34.280621 {"Layer":"4","module":"Image","level":"Warning","msg":"Display layer public/plates/1/4.png"}
2016/12/31 17:17:34.717436 {"Layer":"4","module":"STL","level":"Warning","msg":"Extracting Layer 31 - Z Level 0.9049996"}
2016/12/31 17:17:37.798176 {"Layer":"4","module":"STL","level":"Warning","msg":"Extracting Layer 32 - Z Level 0.9349996"}
2016/12/31 17:17:39.781441 {"Layer":"5","module":"Image","level":"Warning","msg":"Display layer public/plates/1/5.png"}
2016/12/31 17:17:42.857120 {"Layer":"5","module":"STL","level":"Warning","msg":"Extracting Layer 33 - Z Level 0.96499956"}
2016/12/31 17:17:45.218990 {"Layer":"6","module":"Image","level":"Warning","msg":"Display layer public/plates/1/6.png"}
2016/12/31 17:17:45.608200 {"Layer":"6","module":"STL","level":"Warning","msg":"Extracting Layer 34 - Z Level 0.9949995"}

The setup page seems correct and I'm using a stepper for the shutter which is functioning for each layer using gcode before / after layers G1 X18

Thanks in advance, jw