Client Section & no Featured Image

Hello,

I’m missing the Featured Image section on my Clients – the issue is documented elsewhere but can’t find a fix, and the section isn’t present within the Screen Options in the top right either. It was okay a few years ago as I already have several clients in there, but I want to add many more and an unable to do so.

Highend is updated, plugins are updated, WordPress is at it’s latest version but not sure what to do. Before I start disabling plugins etc, wondering if there’s something that can be checked by the team or something technical I can check with my site? Thanks.