[Plugin: Jetpack by WordPress.com] Jetpack's admin bar not showing site stats

I’m in the process of setting up my own dedicated server to host my WordPress site – mostly everything is working, apart from the admin bar site stats provided by the Jetpack plugin.

Rather than get the chart, I get a broken image, and if I try to view the chart directly (i.e. https://wereinthefuture.com.blue/wp-admin/admin.php?page=stats&noheader&proxy&chart=admin-bar-hours&height=20&hours=48) either get a blank page or an error message (the image cannot be displayed because it contains errors).

I’ve taken a look at my apache error log, but it doesn’t have any reference to it at all.

I think it might be broken because I don’t have the correct image processing library installed on my server (i.e. GD or imagemagick), but I’m not sure.

Does anyone have any ideas? Thank you.

https://www.ads-software.com/extend/plugins/jetpack/