Hi Dragos,
Thanks for the reply. Yes, I am (functionally) attempting to change the freq and MGC values exactly as you're example describes so it's good to know I haven't misunderstood the AD9361 User Guide. The primary difference I can think of at the moment is that I am running maximum bandwidth i.e. analog filter=28MHz and sample rate=61.44MHz (245.76MHZ ADC clk).
My "successful" frequency changes are implemented before I enter the "while" loop in main.c.
I'll keep studying the problem....
Stu