Where does the propane go?

But with your reasoning, if the line still contained propane (i.e. it was not somehow lost when the burner valve and tank valve were closed) then that propane in the line would have been repressurized and recondensed as soon as the propane tank valve was reopened, and the subsequent flow should have been immediate propane to the burner that would have ignited. But it does not. Not even a half hearted attempt. Not until a minute or so of flow for the line to refill with the new propane coming from the tank. And that initial flow is enough to blow the flame on a match, so it is not something that slowly builds.

I don't mean to be overly argumentative, just trying to understand the phenomena.