Ok. I've been looking at your Pastebin from Boot Repair, and here's what it looks like to me:
You've got all your partitions listed there, and it's listed which ones contain bootloaders.
/dev/sda1 seems to contain your Windows bootloaders and a secureboot handler
/EFI/ubuntu/shimx64.efi for Ubuntu. I believe there should also be a grubx64.efi in the same directory as shimx64.efi, though, or it won't hand-off correctly.
/dev/sda3 looks like it contains Windows bootloaders and properly configured secure boot bootloaders for Ubuntu.
/dev/sda7 looks like it contains a traditional GRUB2 bootloader (and your Ubuntu installation). If you reboot and open up your EFI configuration tool at startup (just press whatever key the splash screen lists for "setup" or "configuration utility" before that boot splash screen disappears) and tell EFI to boot from one of the two partitions that have GRUB2 installed on it. I would choose the one installed on
If Secure Boot isn't already disabled, I'd disable it. You say in another comment that you have found the option for that.
You may also need to change some settings to tell it to boot from that partition by default, depending on how your EFI setup utility behaves. If you set it to boot from GRUB2 by default, you should be able to use GRUB2 to choose which OS to boot from in future rather than having to use EFI. (The
grub.cfg file reproduced in your pastebin looks like it does contain the entries for booting Windows by handing off to the Windows bootloader.)
If your EFI doesn't provide you with options of which device to boot in the setup (which it typically does do, so I'd be kind of shocked if it didn't give you an option anywhere to configure which device to boot from), there may just be a different key you need to press on the boot splash screen to get the boot device/partition options to appear.
If you can't find these options, perhaps you could provide some images of your boot screen and EFI setup utilities so we could look at them and see if we can spot the setting you need?
There is another option that may be worth pursing if we can't get this to work: properly installing GRUB2 to /dev/sda1 where the Windows bootloader lives. I would consider using partimage or dd to make an image of the partition, first, though. Then, if something went horribly wrong, you'd be able to restore the partition to its original state.