I am also having this issue. I am on AT&T, GalaxyMod RLS16 ROM, KT Kernel(2/7 version). Android version 4.1.1.
The "+" sign is causing problems for me when my allowed contacts are not ringing through to me when the phone is in Call Block mode (I keep it this way while I am at work).
If anyone has any suggestions has a solution that I may have missed while searching, it would be appreciated if you would share. Thanks!
Phone: Galaxy S5
ROM: Not Yet (Stock)
Tablet - Nexus 7 (2013)
ROM - Stock