Lindsey, you already have a concrete reason its improperly installed. Not to mention there is no proper shower drain installed. All they did is mount that dome on top of the tile, and it will start to leaking after short period of time the minute the seal between that and the tile fail. I would hire a professional plumber and have him install the right drain suited for tiled floor and redo the whole floor tile, because frankly speaking, I don't think there is a rubber membrane installed under the tile. @ Lindsey Jordan This product is to be utilized as an aftermarket upgrade, whereas you would remove existing drain cover and replace with this to allow easy removal and cleaning of the 'hair trap'. Looking at your picture, you seem to not have a required drain which will need to be installed to proper drain lines or you will most definitely have problems.
If there wasn't a proper drain to begin with, the contractor should never have gone ahead with tiling until this issue was resolved. Also for proper installation, the original tile should have been removed and proper water-proofing of the shower pan area with code approved draining should have been done, then tile installed. I believe you are going to have to start over and have it installed properly or you will have nothing but problems down the road. Not to mention if you ever want to sell, it will have to be addressed before a sale anyways. I don't know your contractors skill and knowledge level, but if he can't rectify this properly, I suggest you find a qualified professional to remedy this dilemma. @GN Builders, that shower floor that you encountered should be placed in the remodelers 'Hall of Shame'.
A shower floor, like the bottom of a bathtub, is not supposed to be level. Water needs to flow from the wall edges down and into the drain. Using a leveling compound will not accomplish this, as the wall edges need to be higher than the drain. Normally this is accomplished by the contour of the mortar bed base which is below the rubber liner. The Tile-Basin® (patented) has become the most trusted ICC approved tileable shower base in North America. The Tile-Basin® is manufactured with KBRS Hard Core Technology, making it rock-solid, 100% leak-proof (guaranteed) and will inhibit mold growth in the substrate. KBRS has the unique ability to manufacture any shape, or size Tile-Basin® with any drain location that your design.
I can't believe some of the things I encounter during remodels, but this is near the top of the worse I've seen. Thanks for the pictures and post, this should serve as a cautionary tale for checking references and making sure permits, codes, and inspections are followed and documented throughout a remodel.