Materials editing cube preview

I've looked to see if there is a way of scaling up the materials preview cube to get a better understanding of the texture as I find it too small but had no joy. Is this possible? If not, I think it would be a valuable improvement for fine tuning material settings. I think a quarter screen would be more appropriate.

it would be nice if it was bigger and worked. I just ignore the thing now, as nothing looks/renders as displayed by the cube in my experience.

It's so low quality, due to it taking so long to load in early v20 builds! Most other rendering software i have i can scale the preview bigger! Maybe v22?

I've been up in sunny Scarborough all weekend otherwise i would have jumped in too! 
Stumpy called it - Bank Holiday upgrades can be painful without support. 
Thanks to Joe, good shout, I'm just installing to another drive.
Thanks to all of you for the heads up on the issues, I sincerely hope you get sorted quickly.