Similarly I manually remount ESP during install, see post #23 above.
Years ago I did use both Debian and Fedora to see if grub installed to sdb. When I chose sdb, grub installed to sdb with those distributions.
So That narrowed it down to some code in Ubiquity.
I am regularly in Ubuntu forums & AskUbuntu and it seems like every day I or multiple other knowledgeable users have to help someone resolve grub installed to first drive when they want it on second or an external drive.
Similarly I manually remount ESP during install, see post #23 above.
Years ago I did use both Debian and Fedora to see if grub installed to sdb. When I chose sdb, grub installed to sdb with those distributions.
So That narrowed it down to some code in Ubiquity.
I am regularly in Ubuntu forums & AskUbuntu and it seems like every day I or multiple other knowledgeable users have to help someone resolve grub installed to first drive when they want it on second or an external drive.