Strange behaviour of SWD in atollic stm32 nucleo
Sounds quite strange. I wonder if the CPU resets for some reason..
Put a breakpoint in ITM_SendChar() on the line: which says:
ITM->PORT0.u8 = (uint8_t) ch;
I assume that you arrive here first time "AD" is printed.
What happens next iteration when it is time to print? Do you hit the breakpoint? If not, the condition in the if-statement in ITM_SendChar() not met? See if/how they differ between successful print and unsuccessful print.
Use breakpoints to verify that you actually exercise the code. Does that give you any new insights?