Jetpack Installation Stuck 'Unpacking'

Hi,

I was having trouble with automatic updates on my site, and cleared my plugins while fixing the issue. I’ve been able to reinstall all other plugins, but Jetpack won’t work at all.

It goes as far as,

Downloading install package from https://downloads.wordpress.org/plugin/jetpack.4.1.1.zip…

Unpacking the package…

and then nothing – no error message or anything.

I’ve also tried to manually install it, but it hasn’t appeared on my Dashboard. I’m at a loss!