I have an InfoPath form for a SharePoint 2010 List that I've customized with a few formatting rules, i.e. hide a section until the "Status" field is set to a particular value, etc. When editing an item from the list, whenever any rule in the form is activated, all people picker fields in the form completely disappear from view until the item is saved and reopened, at which point they have reappeared and are editable. It doesn't seem to matter if the activated rule directly effects the people picker fields or not - the fields disappear from view. The data saved in the fields does not disappear, and if the people picker field is edited prior to activating any rules in the form, the data collected will be saved (even though the fields disappear as the form reloads from a rule's activation).
I've been creating InfoPath forms for SharePoint Lists for awhile now, and don't remember this issue ever presenting prior to now - it doesn't seem to be restricted to one list either. I've noticed this issue in multiple lists in my site collection over the past few weeks - is there some new bug I am unaware of?