I've read the earnings press releases, the quarterly earnings call transcripts, and the company's 10K & 10Q filings. There is no information so far indicating that MyMagic+ has made a dime.
All of WDW's gains have been driven, as usual, by "higher ticket prices, food and beverage and merchandise spending". This is exactly what's been driving WDW growth for the last 3 years, well before the advent of MyMagic+.
In the business world, "working" means providing a positive return on investment.
There is absolutely no publically available information to suggest that MyMagic+ is "working".