This problem can be resolved using very nice/easy fundamental.
Check in CCC if you have used IP or Hostname to register Database instance,License Server and following this check same in .installation.properties (usr/sap/SAPBusinessOne) if HANA Server is added with IP or Hostname, in short keep those same and for sure XApp would get registered successfully (it was failed on registration).
TIP:- in order to reinstall the XApp dont uninstall whole Server Tools(Mailer, License etc), just remove the XApp rpm using command rpm -ev XAPP.............(get the name using rpm -qa |grep B1) and then reinstall considering that you are using IP or Hostname.
Would remain attentive to hear next from you.
BR,
Parvesh
