I have had this working until the latest update seems have broken it.
I had this item:
DateTime BMPSensor_LastUpdate "Last update [%1$ta %1$tR]" <clock> {expire="60m,NULL"}
it was displaying time in sitemap.
Sitemap line:
Text item=BMPSensor_LastUpdate label="Last update" icon="time-on" valuecolor=[>6000="red",>600="orange",<=600="green"]
Now it does not.