Strange I'm not getting this issue. Can you test it under really simplistic data situation where you've just done a fresh reset and just one small fight to make sure it works at least under those conditions?
I'll see what I can do, although intentionally freezing the game isn't something I look forward to attempting ;)
With a couple of hours worth of data (party, Ogri'la 5-mans), and showing all the data, stack and normalise doesn't lockup, and shows the data in the range 0-100, but the max on the Y axis is 1250, so all the data covers the bottom ~8% of the plot area. Selecting a single fight, or a subset of fights, both lockup.
After a fresh reset I killed an Ogre in the barrier hills, and grabbed the mana thistle next to it. Stack and normalise on this data also locks up. The saved variables for this fight are attached.