31-03-19, 12:29 PM
Had a similar problem when I changed the brake line on my thou. I took the caliper off and suspended it higher than the resevoir. If you've got access to a "hypodermic", you could try reverse bleeding, by introducing the fluid via the nipple and watching for bubbles in the resevoir. One other thought is air getting past the nipple threads. Possibly some ptfe tape wrapped around the nipple. One final suggestion, after you've bled it as best you can, leave it overnight with the pedal depressed, either with a heavy weight or by tying it down to something immovable. Good luck 
Whizz kid sitting pretty on his two wheeled stallion.