It goes to the floor because with the car running it is now power assisted - or power brakes.
I am not sure how the leak would just "stop" leaking.
Just for a note - I blew the seals out of my newly rebuilt calipers I refered to earlier by bleeding them to hard.I know it sounds odd but it happened. Someone told me to bleed them out with the car running instead,and after I fixed the seals _again_ , I bled them with the car running and it worked !!
I am perplexed on your leak........maybe the flare or end that fits into the caliper is dinged up , or not seating correctly.If it was leaking out fluid, it could be sucking air in , and now airbound ??
Wish I was there !! lol - love tackleing the odd quirks.