Left click in the corner where hidden Start button was to open start menu.

i somewhat resolved it using a new feature to override "show desktop" button actions to show start menu when left clicked. it's at bottom as opposed to start button at top which is somewhat inconvenient: gotto move cursor farther, than when clicking (now hidden) start menu button, but ok anyways

I installed beta 5 right away  without testing beta 4 previously
So, the behaviour is as follows:
When clicking in corner on primary monitor, nothing happens. If corner clicked on secondary monitor, Start Menu shows.
I have vertically oriented task bars, but what I have tryed:
* relocating task bar to default position (wasn't able to open start menu when clicking in corner)
* tried 1 monitor only mode: with notebook monitor a single, with external monitor as single (not working)
* changed "main display" between 2 I have, start menu only shows on secondary always, but not works on primary
* disconnected external monitor completely: start menu not shows still

In my tests, the click doesn't work on a secondary taskbar. You can identify whether a taskbar is secondary or not by looking for a notification area - if there is one, it's the main taskbar. Otherwise, if it only has a clock, it's a secondary taskbar.

For the case of one monitor, it should work. Make sure that the taskbar is locked.

Note that even though a single click doesn't work on a secondary taskbar, a double click works. A single click doesn't work due to the way the taskbar is designed. I might look at implementing a workaround in the future.

This feature appears to be broken in version v5.8 (On Windows 10.0.18363)

Works for me on the same version. Did you adjust the "no_start_btn_spacing" advanced option properly?