Thank you for all your help Rita!
“Your material was not measured accurately, so the standard focus height for your material will be used.”
Hope this is not what it reads like.
Does it denote that we cannot de-focus on materials anymore?
If it does I am hoping we can tell it ‘yeah yeah - go away’, like the other messages.
Thanks Rita! I’ll keep an eye peeled for those messages.
I read it as: if scanning is unable to determine material thickness for focus, then either the automatic PG material thickness will be used or the manual thickness you have entered. A manual focus entry will always be used if entered.
going to copy and paste this thread title into my definition of irony lol
I got one of these yesterday. Was a bit surprised by it.
This morning I also got a new one “Invalid settings” It popped up next to the print button, where it would normally show “ready” , “no artwork” and the like.
Unsurprisingly, @rpegg is exactly right. 
Defocus works as before. This just lets you know if the autofocus can’t measure the height accurately. This can happen when your material is an unusual color (e.g. clear acrylic without masking), or if the autofocus laser misses the material and hits the crumb tray.