Flow has been enabled on this talk page about Flow before table of contents in Flow is ready and before a decent search or filtering facility is ready. This, combined with the fact that https://www.mediawiki.org/wiki/Talk:Flow does not load the entire Flow history of discussions, makes it hard to see what has already been discussed. Promises that developers "are working" on table of contents are as old as 6 October 2014, as per https://en.wikipedia.org/wiki/Wikipedia_talk:Flow/Archive_13#Table_of_Contents.3F (Yes, Wikipedia has a discussion about Flow that actually uses working and proven technology making it possible to find things, unlike this discussion page about Flow.) A request for a table of contents in Flow is as old as 11 October 2013 as per https://en.wikipedia.org/wiki/Wikipedia_talk:Flow/Archive_6#Please_provide_indexing_.22table-of-contents.22-like_functionality. Why anyone enabled this half-baked semifunctional Flow discussion system on Talk:Flow is beyond me. He who assumes that a dicussion about Flow is important should not thwart the discussion by hosting it in a broken discussion system. I do not know whether there is any way back, but if there is, using classic talk pages on Talk:Flow should be seriously considered.
Topic on Talk:Structured Discussions
They're (1 developer) still working on the Table of Contents, along with many other things. It should be ready for release next week (during the normal wikitech:deployments schedule, so Wednesday). We can see the ongoing development version at this test wiki. They're also nearing completion on some of the main Search functionality.
They enabled it early, so that editors and developers who are interested in assisting during the creation can take part at all stages. They enabled it in places that have volunteered to test it out, so that the development is constantly informed by real-world scenarios and feedback.
Hey, it's only one and a half year in the making, why do you expect more than this half-baked forum impersonation after such a short time?
After all, they promise us the blue from the sky for this new pet project of the WMF head honchos, once they had the time to spend the multi-millions in their pockets for serious programming.