Hi,
just a "side effect" question. You do

SCON = 0x72; // Mode 1, REN 1

Sure, it selects mode=1 and set REN=1. And it sets bit SM2=1 as well. At such conditions if transmitter sends a couple of bytes with only one stop bit then your receiver will not set RI flag because it recognises stop bit as 9th bit and expects next bit as stop one (=1) but receives the start bit (=0) of a new transaction instead. Be careful about it; maybe try 0x52 value?
Good days!