Me again :-) I'm not sure how to fix this Lava exception. There's an issue on the same communication template as the render exception linked below on line 82 - an issue with the If statement.
Exception: https://rock.northpointe.org/admin/system/exceptions/45597
System Communication with Issues: https://rock.northpointe.org/Communications/System/14
Change the lava from
{% if person.Users | Size > 0 %} ...
To
{% assign userSize = person.Users | Size %} {% if userSize > 0 %} ...