Does anyone has a clue how to add artists pictures to iTunes 12.6?

Hi guys,

This issue or whatever you want to call it, has been happening since previous versions of iTunes. Some of the artists I've got in my iTunes library has or get a picture and that looks great, but others don't.

Is there a way to add those missing artists pictures or force it or something? Those microphone icons just look horrible. Does anyone has a clue how to add artists pictures to iTunes 12.6.0.100?

I thought Apple would fix this in the update from 12.5 to 12.6 but surprise, the answer is no!

I would appreciate any idea or clue.

Thanks in advance folks!!

P.D. Bellow you will see a screenshot about what I'm talking