Apparently, not only do rollover nights not count, but milestone bonuses are for nights stayed in the calendar year only. I queried why, despite being on 54 nights (going from 49-51-54 nights) my 50-night milestone hadn't posted.
The reason was that I stayed:
- All stays that posted in 2018 (60+11 nights)
- 27 Dec 2018 - 1 Jan 2019 (5 nights, credited to 2019 for status purposes but 2018 for milestone bonuses).
- 49 nights in calendar 2019 so far.
Giving me a total of 11+5+49 for requalification, 54 nights under the old rules, and 49 for bonus purposes.
(NB I don't think that was the case last year as I got my milestone bonuses for 2018 based on a total number of nights that included a stay over New Year's.)