Quote not displaying, "0" showing

If I leave a page that has this plugin running open, it goes through and displays the quotes (in random order) as it should, but if I wait long enough it eventually just shows a “0” (without the quotation marks, not in the same styling as the quotes) and it stops there with the zero.

When I check the source code, the <p></p> section for the quotes isn’t being written — it just has this: <div id="quotescollection_randomquote-0" class="quotescollection_randomquote" style="display: block;">0</div>

Any advice as to what’s going wrong/how to fix this?

https://www.ads-software.com/extend/plugins/quotes-collection/