Why is device not showing the phone signal bars anymore?
This is definitely due incompatibilites between the RIL and the baseband/modem firmware. The RIL or the radio-interface layer are the libraries (shared-objects) that allow the phone to talk with the modem firmware. I found this issue on the Cyanogemod JIRA: https://jira.cyanogenmod.org/browse/CYAN-2172 
If you read the comments, you'll see that people have solved this issue by flashing a compatible firmware. 

Since I'm now running Cyanogenmod 11, I dug around XDA and found a leaked 4.4 firmware for my device. It was packed in a CWM-flashable ZIP so I flashed it and voila.

Please remember to backup your device, your current modem/baseband and the RIL files. Flashing a new RIL isn't necessary always but helps.