Tooltip is constantly reseting the backdrop

[zork]

I am trying to style the GameTooltip and am providing my own backdrop. On top I set my own backdrop color and backdrop border color. For items I am recoloring the border by item rarity.

When I am hovering over any item (like in the character window) that backdrop will be visible for a split second but then the backdrop changes to the default one including all color settings.

Has anyone worked with tooltips lately and has a tip on how to handle that?

Btw sometimes I am getting blueish tinted tooltip backgrounds. It mostly happens when hovering over objects like a portal. When you hover over a unit thereafter the blueish tint stays since I am only reseting the backdrop OnShow.

Any hints would be appreciated.