After update to 10.14.6 night shift no longer works on third monitor

I'm running 3 external monitors (all identical Dell U2719D) with my 2017 MacBook Pro. Installed the latest update today to 10.14.6, and now night shift doesn't work on the third monitor (fourth monitor if the internal one is included).

Everything else working as normal. Display settings detects them all as the correct displays, "About->Displays" shows the correct models etc.

Rebooted, to no avail.