OK, good to know that you have found a solution. It probably won't be added to 7+ Taskbar Tweaker, but I'll leave the suggestion open so that other users could leave feedback.

It seems like the option is still there in the new build.

Perhaps you were referring to something else?

Closed as a duplicate of:

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

The notification icons are 16x16 on both Windows 7 and Windows 10.

Can you clarify your request?

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.