Due to a problem with the Frame Buffer II (4K Ready) Intel® FPGA IP when Module is Frame Writer only is selected, you cannot change the Maximum ancillary packets field. That field, under the Memory section of the parameter editor, will be greyed out and not editable.
Frame buffer in frame writer mode, default Ancillary packets = 0
This field defaults to 0 (zero), which will cause all ancillary packets (also known as User packets) to be dropped.
To work around this problem, de-select Module is Frame Writer only, change the Maximum ancillary packets per frame to your desired setting, then re-select Module is Frame Writer only.
Frame buffer with frame writer mode off and Ancillary packets entered
Frame buffer in frame writer mode, note Ancillary packets = 3
This problem is fixed in the Intel® Quartus® Prime Software version 18.0.