Perhaps I haven't made myself clear! It's not the lack of relationship info in marriage indexes or the 1841 census that is the problem with the update. As you say, this has long been the case.
What is happening with the update is that there are now certain situations within FTM where the information to be saved against an individual is not being updated when another person is selected. This results in the wrong info being saved against a person or persons
To use a marriage index as an example, I normally save a husband's record against the husband, then select the wife from the list of partners. Her screen comes up and I save her record against her. Then I bung both source records into the marriage fact.
Now what happens is that if I click on the wife/partner/whatever, although a new screen appears for that person, the info to be merged is stuck with the first person selected - it won't update the info to be saved, no matter who you click on in the screen.
See attachment - the Search Result detail is stuck on Ann Hollis despite her partner being in the main window. It didn't used to do this. Merge "works" but the wrong info gets saved against the person.
[edit] In the example attached, if I click on one of the suggested census returns for William Lowe on the right hand side, the Search Results Detail section stays stuck on Ann Hollis. If I copy the census link from that screen into a new search screen, the Search Results Detail is blank. If I do a brand new search to find the census return for William, the Search Results Detail screen has his info.
Here's a link (needs pasting into FTM, not clicking) to the example with blank Search Results Detail (post new update, it was fine before)
https://search.ancestry.co.uk/cgi-bin/sse.dll?db=uki1901&...