A new, compatible version is planned. More information in the blog post:

http://rammichael.com/7-taskbar-tweaker-for-windows-10-creators-update

There's a ticket about it already:

http://tweaker.userecho.com/topics/651-after-windows-10-creator-update-7tt-says-unable-to-load-library-102/

I have never seen such an issue. You're saying: "Same for NEW INSTANCE". Does it mean that there's an issue when 7+ Taskbar Tweaker is not running, too?

Use the disable_topmost advanced option. Refer to the help file for more details.

Well, the thumbnail preview gets closed when you scroll with the mouse wheel, too.

Awesome program by the way, do you have any information online how it actually works?

Not much. There's an article in a Russian tech website which I have published a while ago.

You can try reading it with Google Translate, hopefully the translation will be good enough.

Not exactly the same, but you can try the Left click on combined item -> Cycle through windows option.

When you shut down or launch 7+ Taskbar Tweaker, it rebuilds the taskbar icons to apply the changes. As a side effect, the icon is placed in the correct position.

As for the bug itself, does it happen when 7+ Taskbar Tweaker is not running? I can't think why the tweaker could cause it.

Does it happen when all of the tweaker's options are turned off? If not, can you try to find out which option causes the issue?