Car: 9th Gen 1.4 Petrol SE + Navi
Join Date: 13th March 2017
Location: Essex, UK
Thanked 293 Times in 263 Posts
Do you know what version of the headunit software you are running? If you haven't had it updated, I imagine you'll be on RC4, As I was (17 Plate) - The RC8 Version I recently was updated to has greatly improved the reliability of Mirrorlink with my Samsung Note 8.
On RC4, Similarly to yourself, I manged to get some indications of functionality, as you describe, but never working reliably.
If you are in the warranty period, you can just go to the dealer and request the RC8 Update with "Mirrorlink isn't working", Or just wait until your next service if it isn't urgent.
If you would rather do it yourself, I have the files and instructions that you can use.