That works.

I noticed that the Manage Rules dialog box shows the formula in your wb to be exactly:
Formula:=D$2=0

whereas in mine, after I entered it just that way, showed
Formula:="D$2=0"

When I removed the double quotes from mine it worked. Excel seems to have inserted specifically what broke the Conditional Formatting. I seem to recall something like this in Excel several versions of Office back. Has that fault been "re-implemented" in Excel 2016 ? Any chance MS will ... fix it ?

Thanks very much.