Updating master bath with walk in marble shower and linear drain. After a few uses, noticed we have an area on the left of the shower floor that does not drain after the water is turned off. I mopped up the small pool about the size of a dinner plate, with a towel after each use. The marble in this area became cloudy after a few uses and has remained cloudy for a week since last wet. Unsure if this is from poor drainage or improper seal. A Schluter 'wedge' was used to establish the slope on the shower floor. It did not extend wall to wall so the tile guy filled in the edges with contract level with the wedge on each side. The right side had maybe 4 in of concrete, the left side maybe a foot (is this appropriate?). We removed the drain cover and with the water on can see the water pools to the left side of the channel from the black support in the drain to the left, there is nothing stuck under the black support. It does drain, just not as freely as the rest of the drain.

Unsure what the appropriate next step is and appreciate the advice from this group. I will add that we had some serious issues with this install on the main floor and are looking for another professional to assist at this point. Lovely Calcatta gold, miserable installation.