Weird Adaptive Cruise issue

Yesterday I was driving on an interstate and cruise control would not engage. However, the symbol for Highway Assist was present. No matter what I did, I could not get cruise control to engage. It seems strange to me that Highway Assist showed as available but cruise wouldn’t come on. Has anyone else experienced this?

I’ll note that it was near sunset but I didn’t receive any glare warnings. I tried to engage at a variety of speeds.