This happens with collection pages that use AJAX to load additional products without refreshing the whole page.
Pre-order Now however only runs once on initial page load, and so products loaded after the initial page load do not get pre-order badges added.
We plan to add support for this type of collection page, but we do not yet have a definite timeline for this.
The only workaround at present is to disable AJAX in your collection pages. We recommend contacting your theme developer to see if this is possible with your theme.