We’re buiding a new shower on attic and use acylic shower pan. Since we ask to protect osb subfloor, so the plumber use a oatey shower liner on the subfloor and build a motar bed on top of it before install the shower pan. Our subfloor is not leveled so the motar bed help level the pan. He used quikrete motar mix (type N), 1) is this correct motar mix? 2) is it okay to use shower liner on the the subfloor? there’s lot of moisture in the mortar mix before it cured and the shower pan is sitting on it and the bottom is shower liner. In fact, the plumber did not level the pan at the first time because he didn’t check the subfloor well, so he has to remove the pan and redo it, after the removed, we find the bottome of shower pan is quite wet even after few days installtion. the second time he finally installed the pan evenly after redo the motar bed but using the same oatey liner underneath, we’re worried all the moisture in motar goes to the bottom of shower pan and can damage the pan in long run. Is there amy problem here? TIA.