Swap partition conflict
I am testing this inside hyper-v so I don't know if it's a general issue or only pertains to my setup. When creating a 1gb disk and going ahead with the formatting, pfsense puts the swap partition size to 1gb and after that the installer fails. I set it manually to 64mb and it worked. Why do you think pfsense is making such a crazy allocation.
In this doc, the setup is how it is supposed to be. In my case, pfsense just allocated all 1024 mb to swap. Weird
The easy install will always try to make 2x the RAM size in swap. If you really need a disk that small, manually sizing the partitions is required. You're hurting yourself more than you're helping by trying to run a full install on a small virtual disk with little or no swap.