grub2 - (Dual Boot) Ubuntu install ignores grub settings

I have two GPT SSDs, from which I intend dual boot Windows 10 and Ubuntu 18.10. Windows is installed first:

• 970 Pro(NVME) with Windows 10


• MX500(SATA) where I want to install Ubuntu 18.10

When installing Ubuntu, I choose to customise my install, and create 3 partitions on the MX500 drive:

• sda1 650 MB EFI partition


• sda2 root partition


• sda3 swap partition

I select dev/sda1 as "Device for boot loader installation"

After the install is completed, I find that the boot loader was installed on the EFI partition created by the Windows installation and the EFI partition I created is empty.

I attempted the process again, with a Win10 install on the NVME drive followed by Ubuntu 18.10, and got the same behaviour. Is this a bug, or a limitation with NVME drives needing the host both bootloaders?

SecureBoot is disabled in case it matters.

As shown by @oldfred in a comment, the Ubuntu installer is bugged. It ignores user input in the "Device for boot loader installation" combobox, and clobbers up the fist EFI partition if finds. Selecting sda instead of sda1 makes no difference (at least on my machine).

The bug is old, first reported in 2013 here https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1173457 and here https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1396379. There are a few workarounds to be found in the reports, but I chose to move to another distribution(openSuse).

Thank you for the support!