I think Steje is right when he says the situation regarding tabs and toolbars is rather confusing, and certainly what he describes I can bear out from my experiences.
In order to see the "problem" in a nutshell, you need to do the following:
In the Preferences\Launching Opus\Default lister select to Ignore toolbars of the Default Lister
In the Preferences\Launching Opus\From The Desktop set up a user command to have Opus load one of your tab groups
Do the same in Preferences\Launching Opus\Startup and Preferences\Launching Opus\From theTaskbar Icon
Now in your desktop create a shortcut to Dopus.exe
If you launch Opus from the shortcut, the toolbars react erratically and incorrectly
However if you launch from any of the methods you have set up in the Preferences the toolbars behave impeccably.
I am sure that some clever person could write a batch file or something to fix the shortcut so that it launched a tab set automatically.
I fixed my problem by steering clear of the shortcut and starting Opus by double-clicking on the desktop.
By the way, the new changing toolbars feature is wonderful. Well done to the Opus crew.