Do you have any other controls like a button that are selected as well?  That would disable the CF.

You should still be able to do the formatting one by one if selecting multiple doesn't work.

Interesting. I don't have an older copy of Access installed anymore, but I could see that being the case.

Scott, I didn't try that.   I was selecting fields in a continuous form.    What I ended up doing was formatting the first field, then using the paste formatting toolbar button to copy the conditional formatting into the rest of the fields.

I have 2021 as well. I found for my continuous form CF worked only on the textboxes. If I accidentally highlighted a label or decorative box by mistake CF was disabled. What I did in the end was hold CTRL down and click the 4 or 5 textboxes one after the other. With them all selected like this CF was still enabled and the formatting worked fine.

Dave, this is strange.  I'm doing the exact same thing, and when I select more than one textbox Conditional Formattng becomes disabled. ????  I wonder if my form has gotten itself into some unstable condition.   I'll have to experiment with a different database using continuous forms.

Screenshot?