It was probably caused by the Anniversary Update of Windows 10, which is not supported in the final version at this time.

See the following post for details:

http://tweaker.userecho.com/topics/599-doesnt-work-on-windows-10-1607-build-082016-anniversary-update/

Here's the relevant topic:

http://tweaker.userecho.com/topics/599-doesnt-work-on-windows-10-1607-build-082016-anniversary-update/

An alpha version for Windows 10 Anniversary Update is available here:

http://rammichael.com/7-taskbar-tweaker-for-windows-10-anniversary-update-early-alpha-version

An alpha version for Windows 10 Anniversary Update is available here:

http://rammichael.com/7-taskbar-tweaker-for-windows-10-anniversary-update-early-alpha-version

That's already possible by using the Mouse Button Control options in the Advanced Options. Please refer to the help file for more information.

No, there's no way to automate it with 7+ Taskbar Tweaker.

If you're a programmer, you can come up with a solution by using the 7+ Taskbar Tweaking Library:

http://rammichael.com/7-taskbar-tweaking-library

There's the option to sort by name in Taskbar Inspector. It doesn't keep the windows automatically sorted, but that's better than nothing, I guess.

This issue exists only for the portable version, due to the syntax of the .ini file entries.

Yes, insider builds are not supported.

There's a post about this:

http://tweaker.userecho.com/topics/65-doesnt-work-on-insider-builds-of-windows-10/