Why did P K Sinha step down ?

Corridors of power are agog with several reports about the resignation of second most powerful official in the PMO, Principal Advisor to PM Narendra Modi since Sept 11, 2019. People are surprised as to why did he step down though his appointment was co-terminus with the term of the Prime Minister. One report says he resigned because of health problems, others say he was ousted from the PMO. Meanwhile there is also a rumour that P K Sinha, the Principal Advisor to Prime Minister Narendra Modi, who  has resigned  is likely to be appointed LG Pudicherry. He is retired IAS officer of 1977 batch.