Could persistent potassium levels below 3.5 but above 3.0 cause symptoms of hypokalaemia? seems odd to have a reference range starting at 3.5 but to tell patients 3.2 isn't "low enough" to cause symptoms. thanks?

Yes. The first issue is your blood being drawn correctly to prevent false increases in your blood K so that your true blood K is being measured. Be sure they draw blood for K after the tourniquet has been released and minimize fist clenching. I have many patients who say they have symptoms of low K at the levels you cite. Go to hyperaldosteroism@groups.io and learn more.