Custom QSPI device for Active Serial Configuration

I am trying to use an S25FL512S to configure an Arria 10 device using Active Serial configuration.

I have created custom configuration device as shown in the Generic Flash Programmer User Guide for Quartus Prime Pro (note that I am using Quartus Prime Standard Edition) and then created a JTAG Indirect Configuration file of my design.

I have then used the Quartus Programmer to load my design into the QSPI device using the instructions listed in AN370. As stated in the system console, the programmer successfully identifies the device (correct device id codes), successfully erases the device and successfully programs the device. However, the FPGA does not exhibit the expected behaviour, indicating that it's not configured correctly.

I've conducted an examine operation and the file downloaded from the device is identical to my .jic file (checked using a hex editor), indicating the problem is with the generation of my .jic file.

In the Program tab in the Configuration Device pop up for specifying your custom configuration device, there is a command called Page Program. In there there is a page size property which is set to 256 bytes. My QSPI device has 512 byte pages which is why I think I am seeing the behaviour I am seeing. The page size property is greyed out and I am unable to change it.

How do I change the page size property to 512 bytes?