All stock apps have a white box around the icon when in taskbar

Hello TenForums, and actually it's my first time to post here. I've long been a lurker, searching around for solutions and tweaks and stuff, but I decided to register because of a minor, rather OCD-triggering problem.

This has only flared up recently, after applying a registry tweak that allows me to run stock apps on a "Built-in Administrator Account" (idk wtf is that, it's my Microsoft account I'm using to sign in my laptop with, for Pete's sake), plus re-enabling UAC. I don't want to undo the registry tweak, since there are a couple of entries needed to be edited/added, and also that I got back to using Edge because Chrome just got too slow and sluggish for me to browse on.

Here's a screengrab of the taskbar with Edge and Groove Music open:

I know it's just small matters, but man, it sometimes triggers the inner OCD in me... I'm running Windows 10 Home Single-Language x64 ver. 1511 with all latest updates installed.

Anyone know the solution to this?

Regards,
Kensta

I supposed no one here knows the problem? It's been pushed back two pages.