add this before your stats:
| fillnull value="0" extracted_field_1 extracted_field_2 ... or, more expansively:
| fillnull value="0" June 10, 2020 at 01:11PM
via reddit https://www.reddit.com/r/Splunk/comments/h0el8f/how_to_display_count_as_zero_when_no_events_are/ftlp4lc?utm_source=ifttt