This affects Magnitude and DateInfo classes.
One approach is to disable caching for instaces of these classes. Another is to ensure they are not mutable, i.e. removing setters. This turns out to be easy to do for DateInfo and I'm looking at Magnitude now.
See https://www.aavso.org/comment/65253#comment-65253 for more details. This is an important bug to fix, hence the high priority. This is a showstopper for the next release (i.e. it must be fixed before the next release).
Magnitude objects are no longer cached, given the complex ways they are currently mutated by observation source plugins. DateInfo is no longer mutable.