I have been testing Upfront fine on my server, but just went to do the same on a third party server and getting chaotic display of of web pages using Upfront theme (Spirit in this case). Clean WP install no extra plugins installed apart from WPMUDEV desktop. Also unable to save any attempted edits of theme in Upfront - editor just hangs. Got the same result using Upfront Builder on another clean WP install on the same server.
Assume the culprit must be lurking in the cPanel configuration which is using 10.1.19-MariaDB. Any known issues with MariaDB or any other likely contenders?