My friend works on the show. Here's some of the goss he's shared with me on her:
"Bscly she was a terror on set in every way. Constantly late (sometimes by over 3 hours, and often she was in her trailer, just didn't want to film), constantly complaining about everything, especially about hours and weather and production speed, making unreasonable demands, snarky and unfriendly to the crew (wouldn't voluntarily speak to them and if anyone but the DP/dept. head spoke to her she'd be extremely cold and act like they were wasting her time).
She was a total diva about her stunts (refused to do jack shit, and then would lie to the media about how much she participated in stunt work- the majority of shots in costume that aren't close ups are not her, even when she's not doing stunts), and after she injured herself she was a million times worse, and was constantly citing her injury for being late, can't do this, can't do that, demanding things, refusing to work on certain days, even tho she had been medically cleared, and essentially majorly overplayed everything, including, again, what she told the media.
There were several times the crew was left hanging for hours on night shoots outside in the rain because she flat out refused to come to set until weather cleared, and would sometimes just refuse altogether and leave. She wasted a HUGE amount of money for the studio on this shit, and majorly pissed off the crew who would be ready to go on time and left sitting in the cold and rain all night waiting for her (they had a much higher ratio of night shooting than most shows, for obv reasons).
Not to mention the fact that she is a terrible actress and would need a high number of takes to get usable footage, something which also irritated her further and made her harder to work with because she was constantly impatient and defensive."
Also apparently "sociopathic narcissist" was a term being thrown around