Can't seem to wrap text (with effects) around a circle?

Short version: To turn lettering into an art brush you first have to convert the text object to outlines. Open the Brushes palette. Drag the converted text object into the brushes palette to create a new brush. Choose Art Brush. The lettering will be visible in the list of brushes. Select a target path segment and then click the lettering brush in the brushes palette. You'll see the line stroke get replaced by the lettering. The lettering will bend the same way the target path bends.

Compound paths can be turned into art brushes. Even grouped objects, such as lettering inside a box, will work.

Multiple things can be done to improve the results of this approach. To minimize distortion I usually find out the length of the target path where the lettering will be applied and adjust the lettering to match that path length. The Document Info palette can show this, but you have to check "Objects" see path lengths of selected objects. I'll often use Variable Fonts that have variable weight and width axes so I can fine tune the lettering before it gets warped in the Art Brush effect.

I attached a sample image showing lettering inside a rectangular box turned into an art brush and then applied to the top portion of a circle. I created a separate path of what I wanted from the circle, determined its path length, then I made the box and lettering match that curved path length before grouping it and dragging it over to the Brushes palette. Very often when this effect is applied the lettering might be backwards or flipped. That's easy to fix by double clicking the brush and adjusting the brush settings.