As soon as I add my own Preset I get this on save:

Message:
Updating css for the physio-medfit theme.Error:{"readyState":4,"responseText":"","status":500,"statusText":"Internal Server Error"}Error:{"readyState":4,"responseText":"","status":500,"statusText":"Internal Server Error"}

... and the front end is destroyed because:
/templates/buildr/css/theme.template.css cannot be found

Hi

Are you working on a live host or local?

Do you see any error in the browser console tab when saving new preset?

Does the site compile successfully when being saved normally?

Do you have security extensions installed?

Are you using the quickstart or the standalone?

Are you adding an custom js or less files?

Regards,
Paul

No security extensions, the only extension is Akeeba Backup. Quickstart is in use. No custom js or less files.

Is there a space in the name you are using?

I've tried and the only thing so far that breaks it is a space