Thanks for responding. It’s not a caching issue… it occurred in all browsers, in incognito, and on the live server and localhost.
I have temporarily bypassed the issue by getting post IDs and then calling get_post on those IDs… I thought that would indicate that there is not a conflict on my site. However, I should have checked this with a fresh WP install, and now I have and I can see that it works there. So it’s something site-specific… sorry about that, please disregard.