Lost/Missing drafts in a session

I had a spiral chat session two days ago, and I had 7 drafts generated in all for a conversation session before I left. Today after two days I see that conversation only has 4 drafts. 3 of the earlier drafts spiral generated have gone missing, I can’t find those drafts nor the chat continuation/discussion which created them. In fact, the end chat is something different which was already resolved before (at draft 4 stage).