How to unarchive iMessage conversation on Messages for Mac

So today, I accidentally archived a group iMessage conversation. That is, I accidentally clicked the ✖ that appears when you hover over a conversation.

In the past, I have done this to conversations with individuals and have been able to restore the conversation simply by searching their name and sending a message. Receiving a message from that person also does the same thing.

However, this time, I am unable to retrieve any of the groups message history through iCloud. In fact, since then, there have been new messages sent by other members of the group, which I see, but I can not scroll up to see any any further than when I archived the conversation.

I have iMessages in iCloud enabled. The archived conversation is still available on my iPhone running iOS 11, as if nothing happened, so I know whatever action I took has not propagated through iCloud to my other devices.

I also decided to do some digging in '~/Library/Messages/chat.db'. My entire message history from the group is still present in the 'message' table. I also found that archived conversation (in the 'chat' table) has had its 'is_archived' field set to 1 and all new messages have been filed under a totally new conversation. I am happy to provide the values of any other table fields if they would be helpful. In a daring act of desperation, I tried setting the 'is_archived' field back to 0 (which I assume was its original value before the accidental archive) and restarted Messages. However, this did not seem to have any effect.

Does anyone have any ideas or solutions that have worked for them? I want to clarify that my objective is not to simply recover the messages from that conversation, as I am fully capable of doing that from either chat.db or the ~/Library/Messages/Archive folder (although I admit I'm not entirely sure what the purpose of the Archive folder is since chat.db has everything going back to my very first iMessage). I specifically want to have my archived messages reappear back in Messages the way the did pre-archive. I also won't be too bothered if I am not able to merge the messages sent since then into the old conversation.

Thank you in advance!