1. Open Plasma settings then Display Configuration page,
2. Select second monitor and change it rotation,
3. Click Apply, the "Keep Display Configuration?" popup will appear, don't click on any button and let the timeout finished to automatically revert the change,
4. For now the second monitor is still marked as selected and its configuration is still loaded bellow it,
5. Simply change its rotation and click Apply

Expected result:
Changes should be applied to second monitor.

Observed result:
Changes are applied to first monitor, even if the second monitor is marked as selected and its configuration is loaded bellow it.