I now have a issue that came from the April 03 nightly. (April 04 Nightly has the same problem as well.)
After I flashed the April 03 nightly when I go to make a phone call I get an error/message "Cellular Network not available". I have a good strong LTE signal and data is still working.
I did a little poking around and found that when I go to phone testing (Dial *#*#4636#*#* ) and go to phone information; the set preferred network type is set as LTE/GSM. If I change it to LTE/CDMA I get my Cellular Network back, but I loose data. Same goes for LTE/GSM/CDMA.
I flashed back to stock and performed a PRL & Profile update, then flashed back to CM12 Apr03 Nightly, and I still have the exact same issues.
What changed between the April02 Nightly and the April03 Nightly that would cause this issue? Does anyone know of a fix?
Edit: Looking at the April 03 Nightly change log I am guessing it had to be something in the new android_frameworks_opt_telephony that is causing this issue.
Edit #2: I found what my issue was. I was on a different kernel and for some reason the CM12 kernel was not updating on the nightlies. I had to flash back to a stock rom and start over with a clean install of CM12. Once I was able to finally get back to the Apr03 kernel my connection issues went away and everything started working again.