That shows its floating height has been saved as only 1 pixel high. (Which may be another problem, but let's focus on fixing it so you can use the toolbar again.)
If you fully exit Opus (via File / Exit Directory Opus), then change the 498 to 298 (leave the 499 after it alone), save the file and re-launch Opus, hopefully it will be visible then.
Failing that, fully exit Opus again, and then delete docks.oxc entirely, to make sure the unwanted toolbar isn't still being loaded and invisible, since it would waste resources and slow down start-up for something you can't see.