Note: Today’s new ROME and Cooker iso’s include updated grub2-2.06-4 which fixes this bug . The bug was with f2fs. If user choose f2fs for root partition then Calamares would not install the grub2 boot-loader. That is now fixed. User should know what they are doing if choosing a file system type other than the default.
f2fs or Flash-Friendly File System is specialized for use with NAND flash memory-based storage devices (such as solid-state disks, eMMC, and SD cards), which are widely used in computer systems ranging from mobile devices to servers.
ext4 or fourth extended filesystem is the default file system type for OMLx installation.
You can find the new ROME iso’s here and the new Cooker iso’s here.