Suite bar theming - background issue

Hi All,

We are in the process of trying to apply new theming (a very simple gradient from left to right) to our tenancies suite bar. We have been through all of the testing, it was looking great so we where about to release it. However when I applied the finalised theming this week, for some reason the styling of the bar changed. 

When we were testing previously the image would be stretched across the entire bar (background cover mode), however now it appears to be applying it like a tile.

I have removed our logo from the screenshots provided below:

This is what it looks like when applied in Admin center and how it appeared in SharePoint etc during our testing.

This is how it appears now when you go to SharePoint or if you navigate back to the Admin center.

This is the bar stretched over multiple screens (replicating what a higher resolution screen would display)

Has anyone experienced this? Does anyone know of anything that has changed?

Cheers,

Ryan