If that upper chimney oring is not sealing it will cause dry hits, been there done that.
one easy way to tell is cover the 4 air holes in the base try to take a pull on the tank and quickly stick your tongue over the drip tip, it should hold a vacuum
if not you are not pulling enough juice into the chamber because of a vacuum leak.
If you don't believe it, remove your upper chimney oring and try it for yourself.
You're both right. If the upper chimney ring is bad or missing it will dryhit while vaping but will flood and leak when left idle for a while. Been there,done that too.