welcome to ft!

in general, a refund will trigger a negative point credit pushed to your hyatt account which may lead to overall negative balance if you dont have enough points in..
While you can in theory abandon this account and open another one, some random audit may lead to shutdown and investigation - not smth i would want to deal with over paltry 30K points

2 stay 10 nt credit is prob from cc - the stay (even prepaid) doesnt post until completed