Soft brake pedal after caliper change
 

2018 Mini Cooper that I swapped out the front right caliper. I was not sure if the threads need to thread tape or not. It did not appear that any were on it when I removed the brake line. It looks like a compression fitting for the brake line vs a banjo connector bolt with crush washers (which is what I am used to.) I tried a two-person pressure bleed which failed miserably. I moved to using a Motive Product pressure bleeder. I started once at the front right - a ton of air came out. I then moved to rear right, rear left, front right again, front left. Things seemed good but after 24 hours the pedal is soft again. I am wondering if I need 1) to tape the threads on the brake line, 2) maybe the line is not tight enough or 3) need to use a scan tool for ABS system bleed. I see no brake fluid on the garage floor. My theory is air is getting in and the only place this could happen would be the brake line attached to the new caliper? Any ideas on how to resolve? Thank you.