It was previously reported via Dave Meltzer of Wrestling Observer that Nia Jax took time away from WWE because she needed time to recharge her batteries but that may not exactly be the case.
Justin Barrasso of Sports Illustrated indicated that her absence had nothing to do recharging her batties but instead she had an issue with the company wanting her to lose clean to Sasha Banks at the TLC event. Barrasso would claim that it was The Rock that advised her to just walk away if she was unhappy with how she was treated.
Here is an excerpt of what Barrasso reported:
The reason behind Nia Jax’s much-discussed “leave of absence” has been uncovered, as Sports Illustrated learned that Jax balked at the idea of losing clean to Sasha Banks at TLC. She called her cousin, Dwayne “The Rock” Johnson, to ask for his advice, and Johnson encouraged her to walk away if she was unhappy.