I haven't been able to get any response from Segger regarding this issue, so I thought I would ask the community to see if anyone else here has had the problem I am currently experiencing with my Ultra+. When I connect it to my customer K64-based board, or even the FRDM-K64F, my serial terminal program just receives an endless stream of null characters. debug_printf doesn't seem to work at all. I've confirmed that my JTAG pins in PEx are configured properly. I actually just switched the JLinkArm.dll so I could use the OpenSDAv2 firmware instead of the Ultra+, and debug_printf magically starts working.
This leads me to believe that this is an Ultra+ issue and not something in my firmware.
Has anyone else experienced this problem and/or know how to correct it? Thanks!