Hmm, it seems to work for me...

Which version of kclock do you have installed, and which KDE Frameworks version (Kirigami specifically)?

I can reproduce error on different computer with Manjaro Stable. I have:

extra/kirigami2 5.96.0-1 (kf5) [installed]
extra/kirigami-addons 1:0.3-1 [installed]
community/kclock 22.06-1 [installed]

When I start kclock, I see these messages:

file:///usr/lib/qt/qml/org/kde/kirigami.2/Dialog.qml:358:37: QML Binding: Binding loop detected for property "value"
file:///usr/lib/qt/qml/org/kde/kirigami.2/PlaceholderMessage.qml:235:5: QML Heading: Binding loop detected for property "verticalAlignment"
file:///usr/lib/qt/qml/org/kde/kirigami.2/PlaceholderMessage.qml:235:5: QML Heading: Binding loop detected for property "verticalAlignment"
qrc:/qml/time/TimePage.qml:18:1: QML TimePage: Binding loop detected for property "implicitHeight"
file:///usr/lib/qt/qml/org/kde/kirigami.2/PlaceholderMessage.qml:235:5: QML Heading: Binding loop detected for property "verticalAlignment"
file:///usr/lib/qt/qml/org/kde/kirigami.2/ContextDrawer.qml:125:9: QML ListView: Binding loop detected for property "topMargin"

Hmm, that's weird, I am currently unable to reproduce this on my laptop with Manjaro.

Your package versions seem to be correct, I am not totally sure why this is happening... Does this occur if you try the Flatpak version?

flatpak run org.kde.kclock doesn't work either.

Qt Quick Layouts: Polish loop detected. Aborting after two iterations.
Qt Quick Layouts: Polish loop detected. Aborting after two iterations.
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: possible QQuickItem::polish() loop
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ColumnLayout
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: possible QQuickItem::polish() loop
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ColumnLayout
Qt Quick Layouts: Polish loop detected. Aborting after two iterations.
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: possible QQuickItem::polish() loop
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ColumnLayout
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: possible QQuickItem::polish() loop
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ColumnLayout
Qt Quick Layouts: Polish loop detected. Aborting after two iterations.
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: possible QQuickItem::polish() loop
qrc:/qml/timer/TimerFormWrapper.qml:108:13: QML ColumnLayout: ColumnLayout called polish() inside updatePolish() of ColumnLayout
Qt Quick Layouts: Polish loop detected. Aborting after two iterations.
Qt Quick Layouts: Polish loop detected. Aborting after two iterations.

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I apologize for the delay, I am waiting on a new version to be released (Plasma Mobile Gear 22.08, but it seems to be delayed) to see if that would change anything.

It's really strange though that I have not been able to reproduce this issue on any of my devices...

Could you please upgrade to v22.09 and see if this is still an issue?

With current version of packages the issue is no longer present and I can add timers.

KDE Plasma Version: 5.26.0
KDE Frameworks Version: 5.99.0
Qt Version: 5.15.6

kirigami2 5.99.0-1
kirigami-addons 0.4-1
kclock 22.06-1 (so I'm not using 22.09)

Seems like the bug was in one of the underlying libraries.