Membership fixed period, not working as expected
For fixed membership type plans, the Fixed Period Start Day and Fixed Period Rollover Day apply solely to the membership start and end dates, not to the payment date. Copying from the explanation provided when clicking on the Membership Type Plan help bubble:


  If membership duration is specified in years, you will be able to specify the exact month and day for memberships to start. If membership duration is specified in months, memberships will start on the 1st of the current month and run for the number of specified months.


So long as your membership start and end dates follow the examples below, then the feature is functioning as programmed.


If you have a fixed membership type configured for a Duration of 1 month and Fixed Period Rollover Day of 2, someone signing up on on May 22 will have the following membership dates:


Member Since: May 22
Membership Start: May 1
Membership End: June 30

If you have a fixed membership type configured for a Duration of 1 year with a Fixed Period Start Day of Jan. 1 and Fixed Period Rollover Day of Nov. 30, someone signing up on on Dec. 1, 2019 will have the following membership dates:


Member Since: Dec. 1, 2019
Membership Start: Jan. 1, 2020
Membership End: Dec. 31, 2020



Note that the Member Since date is always the date that the membership is submitted - this is because the system is not programmed to handle future memberships. The workaround is to create a membership status rule (e.g. called "Future Membership") with a Start Event = Member Since Date and End Event = Membership Start Date and that should not be considered a current membership .

Regardless of your membership type configuration, payment will be processed on the day that the membership is submitted. If your payment processor allows for the selection of a payment start date for recurring contributions, you should be able to solicit a customization from an expert that will allow you to set the desired membership start date for monthly memberships, and then pass the membership start date as the payment start date of the recurring contribution. 

Hope this clarifies things!