If anyone stumbles across this - it's a (at time of writing)10-year old WP multisite "bug": https://core.trac.wordpress.org/ticket/17904

Someone has uploaded some MU plugin code to workaround it here: https://gist.github.com/anttiviljami/01611cf3e74f7e7ae7a6

If anyone stumbles across this - it's a (at time of writing)10-year old WP multisite "bug": https://core.trac.wordpress.org/ticket/17904

Someone has uploaded some MU plugin code similar to Radley's: https://gist.github.com/anttiviljami/01611cf3e74f7e7ae7a6