Gates McFadden had issues with the producers behind the scenes. There's a lot of he-said-she-said going on, but suffice it to say that she spent season 2 doing a Broadway production for $400/week.

https://www.youtube.com/watch?v=IYsemEvV3-Y

It'd be nice to think Star Trek is above the usual Hollywood bullshit, but you read about stuff like this and the experience of Terry Farrel or Grace Lee Whitney, and it's clear that it's in the muck with the rest of them.