Square sheet in middle layers I'm using a Tronxy Ultrabot (looks very similar to Anycubic Photon) and I'm still on my first prints.
Things that happened thus far: many failed prints that stuck to the resin tank, one which I had to carefully scoop off.

What I'm finding odd is that this sheet (for lack of a better term) only seems to happen on one half of the whole thing.

I'm suspecting the FEP film is the culprit here, due to earlier failures. 

What else could be causing this error?
Other info that might be important, the model is using 6 layer, 60s cure time for base; 0.04mm layer size, 10s layer cure time, 1s delay between layers. The resin is Suen Ching

Edit 2: Here's the manual
This is a guess but it may be a problem with the sliced file. Take a look though the layers of the sliced file to see if your software is adding a layer there. sometimes it looks fine in the 3d model but it can add a layer while slicing.