iMessages not downloading!!

I accidentally deleted my iMessage thread with someone this morning after I had backed up my phone last night and now for that person I am only able to get iMessages dates back to March? When I click on messages it is still saying “downloading messages from iCloud” but when I checked after it disappeared no more messages were downloaded past March? I also get the “more photos will be shown once messages finish indexing” and I don’t know what that means?