My main sellers page is a set of blocks with different metrics, but I don't see one that specifies my sales per category.

I assume that is what the new Selling Managers Pro screen looks like

Could you send me some kind of screenshot so I can see what I'm missing

Selling Manager Pro Summary

Thanks Dave, but I don't see anything that will link me to my store category performance. 

My Selling Manager Pro looks like the pic attached.

I've just cropped out the financial data.

That looks suspiciously like the seller hub. That I opted out of as soon as eBay imposed it.

Ah, that makes sense now.

So if I want to see my cateogry performance I have to opt out of the seller hub, which I guess is easy to do.

I just hope there's a way to opt back in!

I'm not sure about opting back in. I found the seller hub to provide very little of what I was interested in and a lot of what I wasn't. I don't even use SMP very often - 'My Selling' provides me what I need to know in a simple linear format. But I'm not a full-time business.