Thanks. Disabling timestamping did the trick and the other references helped with understanding why. Below is my working search after making the change.
index=CALENDAR_SEARCHES | convert timeformat="%Y-%m-%d %T" mktime(CALENDAR_DATE) | fieldformat CALENDAR_DATE=strftime(CALENDAR_DATE,"%Y-%m-%d %T") | makecontinuous CALENDAR_DATE span=1m | chart avg(COUNT) by CALENDAR_DATE
... View more