Check the little hole in the master cylinder. This is a open return hole when lever is released. This is the most overlooked thing in the braking system! From what you have described it doing, this is what I would look for.
Yep! A little more info on what took place before the problem surfaced. There is a alignment procedure also to do when taking the front wheel off, working on the brakes and such.Have you had the wheel off? Could be 2 or 3 things if you have had the wheel off for anything.