Hi ht-users, Let’s try this again. The file I sent the first time was too large. I’m using yt version 3.3.1, and I’ve recently encountered an issue loading data correctly. I’m running SPH simulations of white dwarf mergers and want to know what the mass fractions of different elements are at different times. I have two files that contain the data: 1) a tipsy file, 2) and a text file that contains the mass fraction values of helium-4. The tipsy file loads just fine and I’m able to access the information from the helium file once the tipsy file is loaded. For some reason though, when I have more than 262144 particles in my simulation, yt does not load the helium mass fraction values correctly anymore. I’ve initialized all particles to have a 4% helium mass fraction, and all of the particles up to and including the particle indexed by 262143 have this value, but after that the particles all have 0% according to yt. I’ve checked the helium files directly and all values are at 4%. I’m confused as to why yt would stop loading values correctly after a certain point. I’ve included two tipsy files as well as their corresponding helium mass fraction files. I have also written a script called visualization_test_script.py that makes scatter plots of the white dwarfs showing particles that have correct and incorrect values of helium. I can send more tipsy files if necessary, but they are too large to send any more here. Thanks, Matt