Biggest source of leak is most likely the 'packing gland' on the OPD Service Valve on that Blue Rhino Cylinder
Fully closed no leak
Fully opened no leak
Leaks when in mid travel between closed position and open position
Closed/Opened positions---valve disc is against seat and seals
When opening/closing packing around valve stem is suppose to seal....worn packing leaks
Use up that Blue Rhino and exchange it OR better yet BUY your OWN cylinder.
Blue Rhinos like anything rented/exchanged etc gets beat up/abused PLUS you get LESS propane
And YES/../......your set up is not right as mentioned above (Chris Bryant)
Wrong tape, wrong use of tape, wrong regulator------PLUS lack of pigtail hose with ACME Green Nut (and the safety features it provides)