Trouble reading from On-Chip Flash (gives "0xFFFFF")

I'm attempting to use the On-Chip Flash IP and write a test value to the internal memory at address 0x00000. I would then like to read it back. However, in simulation, avmm_data_readdata gives me the value "0xFFFFF" no matter what I write (even if I write '0').

I've attached my IP settings and waveform, as well as my project files.

Thanks!