I deployed the ArcGIS Solutions for Capital Project Tracking and was digging into the pop up display as I really like the progress bar style visualization. I wanted to see how this worked so I could use it in other places as well. However, when viewing it in the new map viewer it made zero sense, the attribute expressions, which return 'background-color:#hex' needed to display the colours were no where to be found.
I take a look at the HTML in the Classic Map Viewer, and there they are exactly where I'd expect. Why is that? It disappears in the new viewer, and made it so I was unable to create this pop up formatting the same way.
I ended up figuring out a workaround having the expressions just return the hexcode for the colour and putting the HTML in as 'background-color:{expression/expr0}' instead of the above, but is this an expected behaviour or some sort of bug still? Would probably be a good idea to update the templates that Esri is using to work in the new map viewer if it's not a bug.