Since it’s not PG material, Support is likely going to be unable to help.
For help from the forum members it would be helpful if you could post your settings so we know what you’re doing. Also what model (Pro, Plus, Basic) you’ve got
It would be helpful to know what you mean by pieces “dropping out” - while it’s on the bed (material is warped) or after you take it off. The latter is something that’s an issue if you’re designing flat-pack where something stays in your stock until someone pops the parts out & puts it together (like those skelton toys you’ve likely seen). In that case the size of the little tabs that hold things in place is pretty critical.
Also the burn/scorch on the back is caused by flashback from the bed. You either need to mask the material or put a sacrificial layer under the material - like 20pt chipboard.