Supply & Return in each room but room cold with door closed

Good Morning -

House is a 1956 Sold Brick/block house. Forced air (gas) 2015: Bryant 2 stage/viariable speed Gas / AC (13 SEER 410A) Supply & retun ducts in each room System has 2x/year maintenance & runs fine

Problem: even though though there is a supply & return duct in each room, the rooms remain cold when door is closed. Is this normal?

Thanks so much

source https://hvac-talk.com/vbb/threads/2235383-Supply-amp-Return-in-each-room-but-room-cold-with-door-closed?goto=newpost