The Easy Recovery Essentials Win10 ISO (not free!) does not seem to boot from E2B as a .ISO file or if simply converted to a .imgPTN file. The ISO seems to be based on FreeBSD and does not seem to contain the necessary grub2 boot loader for USB booting in an easily-accessible form.
Note that the ISO file can be booted using the E2B grub2 menu system (you must also extract some files and use a FAT32 partition, there is an example .grub2 config file in the \_ISO\docs\Sample mnu Files folder on the 2nd partition).
Note that the ISO file can be booted using the E2B grub2 menu system (you must also extract some files and use a FAT32 partition, there is an example .grub2 config file in the \_ISO\docs\Sample mnu Files folder on the 2nd partition).