Conditional formatting - unable to set field

Hi there EG-1984 

I'm hazarding a guess here: by any chance are there one or more calculation groups in the dataset?

A side effect of adding calculation groups is that the "Discourage Implicit Measures" model option is forcibly set to True. This stops any new implicit measures being used in visuals or conditional formatting settings. Existing implicit measures will continue to work though.

Here's one article describing the issue and what implicit measures are:

https://smootherconsulting.com/learn/power-bi-calculation-groups-and-implicit-measures

The solution (as described in the article) is to create explicit measures with DAX to replace the previous implicit measures, and use these in visuals or conditional formatting settings.

It is possible that the conditional formatting was set up previously, before the first calculation group was created. The existing conditional formatting settings will continue to work but can't be changed without switching to explicit measures.

Regards