3D Inflate won't render (greyed out)

Hello!

I've been using the 3D inflate option for a while, mainly for designing posters. After the text I've put an example of what I did before - draw a square, insert text and inflate. I did it before and I've also seen tutorials where people did it. But a few days ago when I select the square and the text together - it inflates it but the render option is greyed out. When I click on the text it has the option to render - same with the square, but when I select them both to get the wanted design it's suddenly greyed out. Help please!