I'm noticing that the Latex renderer (CTRL+4 or Insert-Tex Math Formula) on Mathematica Online is not currently working. It returns empty boxes in place of the correct rendering of formulas. I'm attaching an example notebook consisting of only a simple Latex formula ( $K3$) but it doesn't work. When I close and then reload the notebook, two (!?) empty boxes are shown reporting an "an unknown box name" failure.

I've already contacted the support but haven't got any reply yet. I've tried on Mathematica Online on both Microsoft Edge and Google Chrome based on a Windows 10 Pro system and on an Android smartphone.

Any idea of how to overcome this problem?

Thanks!