Comment 17 for bug 1053897

Ubuntu flavours <=12.04.1 may cause trouble regarding making a 16bit; or wanting to use a 16bit ESP whereas firmwares are looking for 32bit ESP= no worky!? The workaround is to allow installer to run as it wants to but be sure to copy ESP save in another location then delete 16bit ESP and remake 32bit ESP replacing the files from 16bit ESP before rebooting trying to use U/EFI.
source http://www.rodsbooks.com/gb-hybrid-efi/
"A FAT-16 ESP, on the other hand, seems problematic. Ubuntu 11.04 (and 11.10) in EFI mode creates a dinky FAT-16 ESP, and after my test install of Ubuntu 11.04, the board hung on reboot until I reworked the ESP as FAT-32. Thus, if you plan to install Ubuntu, or any other OS that creates a FAT-16 ESP, be prepared to fix it, preferably before the system reboots!"
"rodsbooks" is an absolutely indispensible source of all things factual regarding U/EFI which demystifies and disproves many myths as well as misinformation regarding this subject.

Again these type of idiosyncrasies appear to be vendor specific.