In particular instances, your templates and campaigns may not appear to be displaying the most up-to-date content that pulled from a data feed. This is due to data feed caching, which in most cases can be resolved with a few steps.
When this occurs, it is important to distinguish whether the caching is occurring at the template level or the feed level.
Template Level Caching
Problem: External URL of feed shows up-to-date content, however old/cached version of feed content appears within the template.
Solution: Make a minor change (additional period or space) to the HTML code of the template, save template, undo change, and save template again. This should push the most recent version of the data feed to your template. There is 20 minute time limit on the data feed cache on templates, so stopping any transactional sends from your template after making your change will finalize the cache clearing process.
Horizon Feed Level Caching
Problem: Horizon feed is showing out-dated or irrelevant content.
Solution: All Horizon feeds have a regeneration time setting that can be modified within Recommendation Manager. Check the "Regeneration Delay Hours" on your feed. If the regeneration time limit has not expired, you can simply click the "Reset Feed" to pull the most recent version of the feed.