I couldn't find any options regarding this, but DF taskbar is being covered by any window. This is not good for a taskbar.
Taskbar should have higher "z-level" of any "normal" window, only "top-most" windows should be able cover it.

Also, because of lack the "top-most" feature, the option "Show taskbar in front of full screen applications when they lose focus" does not work when full screen application is set to "top-most", like a video player.

[EDIT]
Fixed for non-top-most windows in v9.2 Beta 4

I wonder if SetWindowPos: Disallow TopMost Calls option has something to do with this.
I've set it to "Disallow TopMost Calls" because otherwise I had issues when normal windows (non-top-most) would stay behind other normal windows unless I minimize everything and then open the needed window, it happened on monitors with default taskbar too. Once changed that option I've never experienced that issue again.

P.S.
Logs sent via email...didn't realize I could attach it to my reply...

Just a heads-up, v9.0b1 still has this issue.

v9.0b4 still has this issue...
Is there any hope this issue will be addressed before v9 final is released? (just curious)

Because of this issue, tray icons fly-out menu opens behind a top-most window next to taskbar:

Can this bug get some love around here?

Thank you very much!

It works great with regular windows, but DF taskbar still fails go over top of top-most windows when focused.

This particularly problematic if a top-most window next to DF taskbar and you open tray fly-out menu with hidden icons, it displays behind the top-most window. (attached 2 screenshots, first is DF taskbar, second native sytem taskbar)

Another (probably totally unrelated to this) issue is if you have a top-most window overlapping the tray icon fly-out menu (see attached screenshot), clicking on the window within the part that overlaps the menu, will focus the window and the fly-out menu remains opened even though it supposed to close if DF taskbar looses focus.

I'm getting inconsistent results.
If DF taskbar moved to right side and then back to left side, it stays on top of ALL top-most windows, including task manager (which actually stays on top of native taskbar..my guess Windows 10 has different top-most priorities(?))
The fly-out tray menu, however, stays behind top-most window even when that window is behind DF taskbar (see attached screenshot)

After I made that screenshot with W10 native "Snipping Tool" (%windir%\system32\SnippingTool.exe), DF taskbar stopped being on top of other top-most windows just like I described in my previous comment.

P.S.
Using Hoo NetMeter as top-most window, but any other applications can be used for that, tested with PotPlayer, MSI Afterburner

Keith, is there any chances add an option to disable whatever change was made to resolve this "top-most for vertical taskbar" issue?
It seems it created even more issues such as other "normal" windows behave as top-most, or windows open behind other windows and in order to bring the up require several minimize/restore rapid sequences. It's probably a bug in Windows itself, because I had exact same issue when my Firefox extension set it's window as top-most, it somehow affects other windows as well.

We've already saw this problem ...
Active window going back under other non active windows...
... and no way to move it in front!

Please check if this thread in it's last posts can be of any use:
https://www.displayfusion.com/Discussions/View/windows-not-being-brought-to-front/?ID=688d5e24-6834-4c49-b9e5-e3917e152ed0

BTW: My W10 taskbar have this strange habit on main monitor!
Have to open it twice to get it in front.

Alain

It's been 12 days since I installed v9.1 and not a single instance of the issue when other windows can't be brought to front (which I think should continue discuss in different topic

Just installed v9.4 beta2, the taskbar is no longer top most when vertical, so at this point it's safe to assume the issue won't be happening in this version either.

Some new info on the TaskBar mysterious behavior.

Writing from a White PC-
Actual setting - one monitor - No DF installed - fresh W10 few software already installed
(Black PC was 2 monitor with DF installed - 2 years of software install/deinstall)
____________________
On both the same

Vert. TaskBar - Unpredictable random behaviors.
When MouseCallTaskBar:

a) TaskBar appear topmost at first invocation - no reason given

b) TaskBar appear in the back at the first invocation - hide - appear topmost second invocation

>> for > b)
Test:
- first invocation in the back - hide - use other windows - call TaskBar again
>>> it's again a first invocation and it appear in the back

Deduction: if you do twice in a row, invocations obtain a different result, the second is correct
Question: what things are changing inside W10 between Call1 and Call2

Hope it help

Alain