Is the content type format (or whichever format you have tied the toolbar to) actually being triggered?
You can drag the (View ->) Current Content Type drop-down to a toolbar to be able to see the content type (if any) in effect.
You can also hover over the format lock (don't click, just hover) to see where the current folder format comes from. (Part 6 of the Folder Formats: Detailed Guide.)
Content Types in the manual explains how Opus decides when to switch to another content type, using lists of file extensions and thresholds for the % of files in a folder.