Hi Bryn, I have tested it in Thunderbird 52.8.0 in Ubuntu 18.04. It looks different, in that the "plus" signs are now arrowheads, but they do work and expand the sub list well. And the green button works to mark as "read" all the items in the sublist (even if the list is collapsed). I have attached a screen shot of a portion of my list.
I tried to create duplicate emails but it doesn't treat those as a thread (so, no arrowhead) but the green button works to make it "read." Am I trying this correctly? What version of Thunderbird do you have? Thanks G ** Attachment added: "Screen shot of duplicate test messages in Thunderbird 52.8.0" https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/583577/+attachment/5159789/+files/Screenshot%20of%20View%20by%20Threads%20with%20Unread%20from%202018-07-04%2020-13-18.png -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/583577 Title: "View by Threads with Unread" results in no ability to read some messages To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/583577/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs