I got called to a 24 ft above ground. They put the cover on it with the water level just below the skimmer. in about ten days,they don't know for sure, the cover was saging alot with rain water and leaves. The owner looked under the cover and the water had went down to about 8 in. from the bottom. It stopped there. I have looked all around it and found no holes. The leaktrac goes off alot around the cove seam around the outer edge. Could this be a pressure type leak in the seam? Again they aren't sure how old the liner is. It is pretty faded all over and there are alot of rough edges in the seam.
Sneaky Leaks

Confirm the leac trac signal with a dive. Direct visualization is the only way to confirm with a dye test to see whats going on. Hope you have a dry suit.

With 8" water left going to be more like a paddle with a dye test

My bag i thought he said water loss was a total of eight inches. Yeah, no need for diving this one. hop in the pool and look around you should fihd something without having to don the tanks on this one. LOL

Didn't read all the responses maybe this has already been stated.
In above ground pools > 95% of the time damage in above groundpools is in that cove area. No mysterious pressure leaks just simple damage that in a dirty pool sometimes gets plugged w debries or sediment leading the homeowner ththink the water has reached it's level

Could it be termites in the sand that forms the cove ? Liner change coming up, don't you just love those overlap liners