Storage not able to write, but Flash can?

Sorry, worked it out - I had misunderstood the process.memory readout! It reads: flash_code_start: 1610612736, flash_length: 524288

So I just did this and everything works:

f=require("Flash");
for (i=0;i<524288;i+=4096) {
  print("erasing:",i);
  E.kickWatchdog();
  f.erasePage(1610612736+i);
}