in my case i just inspect that icon that i need
then copy > copyOuterHTML
<span class="ms-list-addnew-imgSpan20"><img id="idHomePageNewItem-img" src="/_layouts/15/images/spcommon.png?rev=43#ThemeKey=" class="ms-list-addnew-img20"></span>
then use your own custom images by custom css
I created a bug report with Microsoft shortly after creating this question and quickly found that several other people were having the same issue. Microsoft confirmed this to be a bug with how web parts share access tokens.
My ticket got combined with another slightly different but similar issue related to the same token sharing functionality and while I ...