3170208 - Fiori Approval App shows wrongly encoded characters when having a non-unicode backend-system in SAP Invoice Management by Open Text

When you are working with the Fiori Approval App or the Enter Cost Assignment App, it might happen that special characters within comments show wronlgy encoded UTF-8 characters, like ä ö ü.
This is only happening if the comments had been entered in the Fiori Apps, the characters are shown correctly if a user has entered them in the backend system (SAPGUI). 

SAP Invoice Management by Open Text

UFT-8, non-unicode, Fiori Approval App, encoding, special characters , KBA , XX-PART-OPT-INV , SAP Invoice Management by OpenText , Problem