The file may be too large Lee, what size is it? I think the limit is 10 MB. If the file has many measurements in it you could save individual measurements into their own mdat files, or you could try to zip the file and attach the zip instead.
There are some big resonances below 100 Hz, also pretty high distortion levels. You are measuring a large space so you should use a longer right hand window, 1500 or 2000 ms, and don't use a frequency dependent window - it will obscure the resonances. I'll look at the measurements in more detail tomorrow.
Here are the overlaid SPL traces, showing the low frequency resonances. The SPL figures seem very high, does the UMM-6 cal file have sensitivity data? May want to go through SPL calibration if it doesn't. If those are actual levels they are much, much higher than needed for measurement.
Here is an example of the distortion I mentioned, pretty high everywhere, perhaps because the levels are high:
Looking at the curves is it possible the gain structure or your system is upside down? Meaning the amps are wide open and the board is throttled back? Might consider pumping a reference level thru the board and setting the gain structure then setting amp gain with an spl meter for starters. the levels you show are uncomfortable and over stimulating the room and will certainly cause distortion.