Igor, can you please post a screenshot of the taskbars from both monitors, while they are as narrow as possible?

Thank you for the suggestion. There's already a topic about this feature, so I'm closing this:

https://tweaker.userecho.com/communities/1/topics/285-center-superbar-icons-windows-78

What do you mean by "open the explorer"? There might be a slight delay on startup before the option is applied, if that's what you mean. And of course, the tweaker should be set to run on startup. Otherwise, if you say that it works, I don't understand the problem (and what "don't group" has to do with this).

I don't know. My best guess would be that some program on your computer prevents the tweaker from operating.

I tested on my Windows 7 with all recent updates, and the tweaker works properly. It probably has something to do with your PC configuration.

The CreateRemoteThread function fails on your computer, if that helps.

Is your taskbar vertical? For a vertical taskbar, the option doesn't work. Otherwise, It should work like this:

The video didn't arrive. I got the mail, but the link didn't work. Please try again, otherwise I have a hard time helping you blindly without knowing what's going on.

I looked at it. The 1003 error means that the tweaker failed to run the injected code as part of the explorer’s process.

This can be caused by an antivirus, which denies access to explorer due to security concerns.
Which antivirus are you using? Can you try to whitelist the tweaker and report back whether it solved the issue?