Missing letters on drive buttons

I'm not sure what happened to the letters (A, C, D, etc.) on my drive bars in Directory Opus.

I have "show label" checked, and I've tried left, right, above, below, but I can't get them to display. What else do I need to change?

Can someone post the default settings for the drive toolbar(s)?

Check that labels are enabled (or set to "default") for the overall toolbar in the Customize dialog. That setting overrides the one on individual buttons.

Thanks. I looked into it and found out that the Drives toolbar was set to display the labels, but the drive labels still did not appear.

Eventually I discovered that the problem was that at some point I must moved/dragged the Drive buttons onto the Tabbar toolbar, which has its label state set to "off" by default!