This question pertains to notmuch built from recent git HEAD, using notmuch.el in show mode (i.e. not tree mode). I sometimes read a thread with a bunch of messages and notmuch.el collapses a bunch of them (even if unread and the search matches tags in every message). I can't figure out the heuristic notmuch is applying here. In particular, pressing SPC does not seem to navigate to the collapsed messages (again, even if they are unread). Worst case: only the first messages is initially expanded and all subsequent are collapsed. I press SPC and the cursor goes to the end of search results. SPC again all the entire thread is archived. This behavior has caused me to accidentally skip messages. First step for me is understanding what is going on so I can fix it.