Pool losing water RAPIDLY just plastered

Hi everyone. I just remodeled my pool owner/builder but hired a plaster co. to apply 3m to my pool. It looks terrific-BUT..... I had the pool replumbed, new lighting (sam), skimmers, suction cleaner line, auto-fill, 2 pumps, heat pump, and waterfall which also meant new decking and tile. I have a company doing an acid startup so my equipment is not running at all. I am losing several inches of water very quickly. The pool was full yesterday to the top of the tile line at 2pm and was down below the tile line by 11pm. What could cause this? I filled it again today with the same result. I have a 25-30k gallon pool so a water loss like this is going to be pricey. The plaster people seemed indifferent and said that it is probably a plumbing problem but they would get someone out sometime tomorrow. There is no water that I can see anywhere. Anyone have any thoughts? I am scared to death because most of this they would deny responsibility for as they didn't do the work. Is it typically the plasterers responsibility to make sure everything is sealed tight with no leaks? I have not yet paid them for the plaster.

They should have done a pressure test on the plumbing before plastering in order to pass inspection. If so, then the leak is probably around the skimmer or lights where they meet the pool surface.