Numerical simulations of magnetization stability in <1 µm diameter magnetite (Fe3O4) grains have long predicted that particles in the 80 to 160 µm diameter range have anomalously low stability, expressed as low temperatures necessary for remagnetization. These particles may contribute to a range of 'non-ideal' behaviors in paleomagnetic samples that complicate their interpretation, especially for paleointensity studies. We search for evidence of this behavior experimentally using the quantum diamond microscope, which can detect and quantify the magnetizations of particles in this size range. We find that, indeed, approximately 15% of particles appear to demagnetize during heating to less than 330˚C. We isolate a few particles for ongoing slice-and-view tomography to retrieve three-dimensional reconstructions of their shape, which would help us understand why particles have anomalously low demagnetization temperatures within this size size.