Did you ever get resolution? I have multiple iPads and iPhone which for many months if not longer have had the similar problem if not the same. I have a text thread that has a bunch of multimedia attachments documents whatever. I go to the contact summary in the Messages app within the thread and look at the tiled summary of information sent and received, but it’s all missing or much of it is sporadically missing in different on each device.
The text thread itself contains everything, but the summary does not and if I toggle off and back on Siri and search functions within the settings the items seem to reappear, but then can go missing again. I think it’s been a long running bug that people don’t pay attention to our understand ,
I have a case open with Apple but no solutions or resolutions found at an escalated level. It’s still ongoing. I reported it myself at least as far back as iOS 17.3 but they said they had no record which is odd but anyway did you find a solution or still, the same as mine, but the tiled summary does not also seems to affect the interpretation of cloud storage or on device storage