Vector smart objects from Photoshop are invisible.

That's an odd title, but let me explain the issue…

I can paste a graphic from Illustrator CC 2021 into Photoshop CC 2021 as a vector smart object without issue.

However, when I double click the vector smart object layer in the layers panel to open it in Illustrator for editing, the paths are there, but regardless of the fill and/or stroke colours the Colour palette is saying are applied to the object(s), it is invisible. 

I can select, resize, and move it. However, when I try to select a different colour, it doesn't take effect. The fill and stroke colours change in the Colour palette accordingly, but have no effect on the object.

See attached screenshot.

I posted this in Photoshop as well since I can't tell if it's a PS CC 2021 issue, or an Illustrator CC 2021 issue.

Anyone else having this issue and hopefully found a resolution? It's probably something super simple, but I can't figure it out.

Thanks.

15" MacBook Pro - Mid 2015

OSX Catalina 10.15.7