Renders not working in Prmiere v26.02

I’m trying to render a few small sections of my timeline (<30secs) but it refuses to render and just sits there with the render bar not moving (all night!). Some clips contain object masks but I’ve removed these and it still happens. I reset the preferences and cleared the cache and it rendered a few that it wouldn't render before but then stopped again. It’s like it's getting ‘clogged up’ somewhere and can only cope with with a certain amount. It also won’t export so this is an urgent bug fix request!

My system is:

timeline: 23.976 fps, 4096x2160, ProRes422.

Version 26.02 (build 2)

MAC: MAC STUDIO 2023 M2 MAX 96GB TAHOE 26.3.1 (a)

Sandisk Pro Graid 80Tb shuttle 4