NOT ONLY + present perfect continuous (inversion) + BUT

Point 92 in the category of PAST is defined:

present perfect continuous, invert the subject and affirmative auxiliary verb with ‘not only … but’ as a focusing device

EXAMPLE:

Not only has Pablo been talking publicly for the first time about being an orphan,

but together, we started a live storytelling series we’re calling Talk Rx,

and it’s become really popular place for his peers to show their most vulnerable and powerful thoughts and feelings.

TED