Magura brake bleed issue

[peggysue]

Need some advice, have a raceline rear lever, all was fine. Fancied a change and purchased a jitsie lever. But I can’t get a bleed on it at all. Once bleed kit is removed it feels empty. If I wind tpa in I get some feel, but it’s spongy. Literally like it’s full of air. Gave up after maybe 20 bleeds. Can’t bath bleed as it internal routing. So put my raceline back on and now same problem. New bleed kit too. Bleeding from slave up to lever. I’ve noticed when I let my thumb off the syringe at the slave end water goes back down the bleed tube at the lever and pushes the syringe back at the slave. So by the time I’ve removed tube from lever and replaced bolt it’s empty. Then I remove the syringe from the slave and water starts leaking out the slave bleed port before I can get the bolt in. I’ve bled hundreds of brakes over the years and never had this. New olives and shroud nuts. Tried everything. Anyone got some advice ?