BPM Inbox not displayed, gives Javascript error

Hi,

I am trying to open the BPM Inbox via https://<host>:<port>/bpminbox, but it throws a Javascript error:

Uncaught TypeError: Cannot read property 'dataServices' of undefined in ODataMetadata.js:13

If I remove the roles UnifiedInboxUserRole and com.sap.bpem.Enduser, the BPM Inbox is shown fine, but it states correctly I don't have the appropriate roles.

Have I missed some configuration? The standard UWL works just fine