Need advice on next step for leak

[Challenger13]

20x40 vinyl everything but pool walls replaced 5 years ago. Rather suddenly I noticed a loss of a little under 1/2 every 12 hours . I had just added some ph up then ph down to balance water . Bucket test confirmed . Seem to lose same with pump on or off. Put gizmos in skimmers plugged returns. Still losing . No air in basket great pressure. Repaired spider crack in skimmer replaced cracked return line faceplate. Still leaking. Spent hours searching pool for holes / tears used dye around skimmers returns do not see anything suspicious couldn't open covers to main drains but did squirt some dye didn't see anything suspicious. What's my next step ? Pool guys are all busy but do I get lines pressure tested ? Hire a diver to search the pool ? Hire leak detection ? Thanks for any advice

[randypape]

hello,
did you figure this out,,, I have the same problem?