Additionally tested on another machine before the update to 6.4.0, running Arch Linux/KDE Plasma 6.3.5/Frameworks 6.14.0 and the search functionality worked as expected.

I tested this using a top Application Menu and Dolphin and can reproduce the issue of search returning no results.
Search produces no results, it doesn't seem to do anything. 

I saw no other strange behavior, and was unable to reproduce the other behavior of the Search field. Would it be possible to attach a screen shot or recording of what you're seeing?

Reproduced on git-master and Fedora 42 6.4.10

Created attachment 182618 [details]
Screen recording of strange search behavior when re-triggering the search action

Attaching a screen recording of the strange search behavior to demonstrate the issue

(In reply to amy from comment #3)
> Created attachment 182618 [details]
> Screen recording of strange search behavior when re-triggering the search
> action

Thanks for the recording, I see what's happening clearly. It looks like the menu under Search includes things from all the other menus (File, Tools, Help, etc)

Can also reproduce the issue.

This widget hasn't had thaaaaat many commits in the past few months: https://invent.kde.org/plasma/plasma-workspace/-/commits/master/applets/appmenu?ref_type=heads

If it's not one of those, it could be a Qt regression.

I tried putting in some debugging effort and couldn't find the cause of the issue, but what I did find is that the AppMenuModel does appear to have the correct internal state, including when searching in response to keyboard input. Logging the m_currentSearchActions for each keystroke shows the correct results. From what I can tell, the issue seems to be somewhere between adding the actions to the searchAction menu and displaying the menu on the screen, or signaling that the state has changed.

A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/5650

*** Bug 507041 has been marked as a duplicate of this bug. ***

A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/5690

A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/5693

Git commit 5f18319f3bf15c5d92321473850b3fbae6a2f5b5 by Niccolò Venerandi.
Committed on 22/07/2025 at 14:42.
Pushed by niccolove into branch 'master'.

Reparent menu actions to the temporarily created QMenu in global menu

Otherwise, the search action will try to manipulate the menu of the
search action, but it will only change the empty one, and not the one
that we are displaying. By reparenting we make sure that all changes
are applied to the shown menu.

M  +6    -0    applets/appmenu/lib/appmenuapplet.cpp

https://invent.kde.org/plasma/plasma-workspace/-/commit/5f18319f3bf15c5d92321473850b3fbae6a2f5b5

Git commit e1824f2f698bb360233837df19473911b98c5b51 by Niccolò Venerandi.
Committed on 22/07/2025 at 14:43.
Pushed by niccolove into branch 'Plasma/6.4'.

Reparent menu actions to the temporarily created QMenu in global menu

Otherwise, the search action will try to manipulate the menu of the
search action, but it will only change the empty one, and not the one
that we are displaying. By reparenting we make sure that all changes
are applied to the shown menu.


(cherry picked from commit 5f18319f3bf15c5d92321473850b3fbae6a2f5b5)

Co-authored-by: Niccolò Venerandi <niccolo@venerandi.com>

M  +6    -0    applets/appmenu/lib/appmenuapplet.cpp

https://invent.kde.org/plasma/plasma-workspace/-/commit/e1824f2f698bb360233837df19473911b98c5b51