From what I can tell, there's a bug with the new lowered values for rapport thresholds. I'm copying what I wrote in those threads, since it's the same issue. According to this thread, the solution below works.

Here are the new values with the old values in parentheses:

Default: 750
Friendly: 1000 (1500)
Close: 2000 (2750)
Allied: 3000 (4000)
Companion: 4000 (5000)

It seems that if you had between 4000 and 5000 rapport with the companion when the patch dropped (so Allied under the old values, but not yet Companion), the menu displays you as having Companion-level rapport with the companion and their dialogue is correct, but you don't get credit for the achievement. It's possible that this is because the achievement progress is triggered specifically through gaining rapport that pushes rapport from Allied to Companion, but if the companion's rapport was already at 4000, this technically never happened, since the rapport threshold changed without any actual change in rapport.

Based on another thread, I believe it can be fixed by doing actions that decrease the companion's rapport until it falls below 4000; then you can do things that raise the companion's rapport back to 4000.

The most disliked actions for each companion (excluding Sharp and Azandar; they aren't affected because the patch that lowered rapport thresholds also added them to the game, so it's impossible to have had them unlocked when the rapport thresholds changed):

• Bastian: murder (-25); this one may have no cooldown and may also get you an additional -10 rapport for attacking an innocent.
• Mirri: using the Blade of Woe (includes killing enemies, not merely non-hostile NPCs) (-25, -5 during cooldown).
• Ember: pay a bounty to a guard (-25, -5 during cooldown); Ember also dislikes getting caught committing crimes (-10).
• Isobel: murder (-10, -1 during cooldown).

Unfortunately, the maximum rapport is still 5500, so if it's all the way at the end of the bar, it'll take a lot of annoying them to drop them below 4000.

You can check the companion's rapport value with /script d(GetActiveCompanionRapport()) in the chat window.

PrinceShroob wrote: »

From what I can tell, there's a bug with the new lowered values for rapport thresholds. I'm copying what I wrote in those threads, since it's the same issue. According to this thread, the solution below works.

16BitForestCat wrote: »

This just happened to me as well. I reached max rapport with Ember a few days ago, and nothing's been unlocked. Did a search on the forums and found this post. Recommend everyone having this issue file a bug report through your account at https://help.elderscrollsonline.com/app/ (reports in-game tend to be ignored). Click "Submit a ticket" and then "Feedback/bug."

Thanks a lot for your advices! I'm glad to know that I'm not alone with that issue. I'll open bug report about this, perhaps devs can make a fix and workaround about it (not sure if I really need Ember's keepsake right now, so I'll stick with 5500 rapport for now)