Hi,
There is obviously an issue with you compiling the SW and /or the modifications you have made.
I suggest you start from the basics (snd /rec) by using our example code.
Eg examples 5a/5b or 6a/6b. These are basic examples for two way ranging and can be flashed onto your boards (after compiling)
You could maybe also connect PC Decaranging to one of the boards and check what is send by the TAG. See EVK and PC Decaranging user manual.