Just adding my comments for others reference.
After raising ticket with Qlik the Qlik support guy doubted on port 8080 with http.
Actually from QMC we were using http with port 8080 (not using default port 80) so due to some reason the request coming from client app was being rejected. The moment we changed the port to 80 it started working flawlessly. We are still investigating this port 8080 issue with Qlik support. The problem seems to be in April release (of qlik sense client).