China having power and presence is one of the obvious reasons for this shift in this region, however if we look at it more closely then we see that the former president Mr. Mohamed Nasheed was pretty much in favor of an "India First" foreign policy in fact he has been quoted saying "India-first foreign policy approach is probably the only sensible foreign policy view that we should have in the Indian Ocean”. Now the current president Abdulla Yameen Abdul Gayoom is bringing in the shift in the following forms (following quote is from this article of a renowned newspaper in India):
Ever since Nasheed, the first democratically-elected President of Maldives, was made to step down after a series of events that has been described in some quarters as a coup, the Indian Ocean archipelago is witnessing political tussles. Nasheed had taken refuge at Indian High Commission once, fearing arrest under the regime of his successor and former Vice President, Mohamed Waheed.
Above that add some of this (An internal government shift to the other side):
Maldivian government took several steps to bolster Mr. Yameen's authority such as removal of Chief Justice, police chiefs and arrest of Vice President and former Defence Minister. These incidents earned widespread condemnations from various countries, including India. Prime Minister Narendra Modi skipped Maldives in his Indian Ocean tour.
And then this (A business relationship with an Indian infrastructure company strained):
Relations between India and Maldives came under a strain after Male had terminated the agreement it entered into with GMR in 2010 for the modernisation of the Ibrahim Nasir International Airport. The airport was taken over by the Maldives Airports Company Limited after a high-voltage legal tussle in which GMR.Maldives government maintains the reason for cancellation of the project was because "the contract was illegally awarded" by the then President Nasheed. The country's anti-graft watchdog has ruled out any corruption in the leasing of the international airport to GMR. The airport expansion project was subsequently given to the Chinese company, which will plough in US $ 800 million. GMR, meanwhile, has won an arbitration against the Maldives.
Taking all this in account you can easily see the shift coinciding with the appointment of the new President and his policies which seem to accomplish stability for his nation in a "not so democratic" way in the long run.
So the change in political climate and the regime's policies is the reason. Such policies are naturally favoring an inorganic growth which china is readily providing, unlike India which prefers a more democratic (or bureaucratic or naturally slow) approach which is failing to fulfill the aspirations of the new President in one way or the other.