The URL behind "HTML5 UI" includes the VM-ID in lowercase, while the VM-ID in the vCenter is uppercase.
Example:

The referenced URL in Icingaweb2-VsphereDB:
https://<vcenter>/ui/#?extensionId=vsphere.core.vm.summary&objectId=urn%3Avmomi%3AVirtualMachine%3Avm-3675318%3A88z882a0-56a6-414c-tkqq-f16d77g21mtz&navigator=vsphere.core.viTree.vmsAndTemplatesView
The URL in the vCenter:
https://<vcenter>/ui/app/vm;nav=v/urn:vmomi:VirtualMachine:vm-3675318%3A88Z882A0-56A6-414C-TKQQ-F16D77G21MTZ/summary
This results in clicking on "HTML5 UI" does not work:

The URL behind "HTML5 UI" includes the VM-ID in lowercase, while the VM-ID in the vCenter is uppercase.
Example:

The referenced URL in Icingaweb2-VsphereDB:
https://<vcenter>/ui/#?extensionId=vsphere.core.vm.summary&objectId=urn%3Avmomi%3AVirtualMachine%3Avm-3675318%3A88z882a0-56a6-414c-tkqq-f16d77g21mtz&navigator=vsphere.core.viTree.vmsAndTemplatesViewThe URL in the vCenter:
https://<vcenter>/ui/app/vm;nav=v/urn:vmomi:VirtualMachine:vm-3675318%3A88Z882A0-56A6-414C-TKQQ-F16D77G21MTZ/summaryThis results in clicking on "HTML5 UI" does not work:
