We have loads of "conversations" that are primarily streams of messages posted via the API. It's quite frequent that we need to find something in these streams, however there's no way to search them currently.
The global missive search seems to only return results for regular chat messages and emails, which doesn't make much sense from a user perspective.
In general search in Missive is the biggest (only?) real issue we have with the platform.

Photo Viewer

View photos in a modal