This is not the same issue as the one the pre-Windows 8.1 Update 1 version.
Please see my reply here:
http://rammichael.com/7-taskbar-tweaker/comment-page-17#comment-3660

v4.5.1

v4.5.1

v4.5.1

v4.5.1

You might want to try the auto-hide taskbar setting.

Read about the Advanced Options Editor here:
http://rammichael.com/7-taskbar-tweaker-v4-4

Yes, I could reproduce this. Seems like an (accidental?) feature.
If you're asking whether it's possible to "just" put back the tray icons on your main monitor, than the answer is no. The main taskbar and the secondary taskbars work in a different way. Even though they look the same, and use the same task list, the outer controls (i.e. the taskbar itself) have different code bases. That's why they require different tricks to remove the width limit.