It's hard to check when your game is already finished to be honest. I guess you need to get back in act 1 before raiding a grove? That's a lot of time to check it. But as you describe it's definitely bugged if it requiers other relationship before raiding just to make flags work correctly. And still it won't be completed character because "alurlssrin" like problems.
The first time I didn't get it (high approval iirc) then after blasting her approval to 100 it showed up.
For my character 100% approve was at the middle of act 3 or earlier (no more approve triggers). Nothing happened.
In my save I was partnered (starting mintharas relationship ends all your others), maybe same bug?
In my save I have no relationships at all except Minthara. Denied every other companion.
