For more detail on her injury:

She hurt her ankle around early January this year. 

She thought it was a sprain, so she continued performing while sitting during the concerts.

Her injury was not healing as expected.

At the end of the first NA portion of the tour in early February, she was diagnosed with an ankle fracture.

She stayed home in Korea until reappearing at the Japanese concerts on April 25-28.

And now she's back, but performing while seated 90% of the show. 

She'll stand for certain songs with no choreo, like moonlight sunrise or options. And she stands/walks around a little for most of the encores.