companions, at least Mirri from what i observed in my case, have a cooldown between the times getting rapport.
This is not even specified in the wiki. If you read a bookshelf and get rapport with her, then kill a goblin, you won't get rapport for the goblin even though they're different activities. It's like it has an internal cooldown not just for the same activity but also for others. And i think this Ashlander daily quest is affected by this, while the Fighters Guild is not (even though once it happened to not get rapport from here either).

There's also other missing informations in the wiki, for example showing her the Thieves Guild stolen collection awards 5 points after some time even though wiki says 75 with cooldown, i tried swapping places like showing the Vivec Library instead and waiting more than 24 hours between each visit, still 5 points but the first time i brought her there it gave 75.

It works for me, but perhaps it worked only because of the timing between handing in the Ashlander daily and my previous activities ?

@qwaurck : that behaviour sounds like a bug, it seems to me that if you hand in the quest while mounted, the result should be the same as when not mounted.

@Sergykid : I was hoping the 75 for showing Mirri all her favourite libraries/museums was repeatable, now I feel let down that subsequent visits will add so little rapport.