As per https://github.com/backdrop/backdrop-issues/issues/309, can we also add in this functionality: Field Word Boundary? This module allows trimming to word boundaries, not just sentences or paragraphs. Seems like a logical addition to core...
(I think the problem this solves is most often seen when the trim length is quite short (e.g. 100 characters) and the first sentence is longer than this - this means that nothing gets output).
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I use Lando (a wrapper for docker) and find settings changes happen straight away
How often is the settings.php loaded.
You might need to add a Relationship in the View to Flags. Or there might be a setting on the content type. I can't recall for certain but I think it's possible.
No Flag fields in Views
Try using caching in the View settings, set to 24 hours. This should work for anonymous site visitors.
View to show a different node each day