I know this thread is kinda old now and the  OP gave up but for anyone else who stumbles in here looking for answers:

I'm almost 100% sure that the OPs issue has to do with partition mapping. It sounds as if windows was installed in UEFI mode instead of the old MBR bootcamp fashion. Windows requires one or the other. Installing Ubuntu automatically converts the disk to "mbr hybrid gpt" and it has to be converted back to true GPT before windows will boot. This can be done with "gdisk" which someone explains above. To my knowledge gdisk is the only safe way to do this without loosing data. 

NOTE: Ubuntu 22.04 and possibly later versions have "os prober" disabled by default which prevents grub2 from booting windows properly. This can be fixed by adding a certain line to the grub configuration and saving the changes. 

    sudo nano /etc/default/grub

Gets you to the file. Under the other parameters add

    GRUB_DISABLE_OS_PROBER=false

save the file with "ctrl+x" then "y" then "return"

    sudo update-grub

ALSO NOTE: If windows EFI is indeed corrupted it can be restored from a windows install disk or system repair sector using diskpart in the terminal. This will overwrite grub and possibly the macos efi files. Mac doesn't need efi to boot from holding down option and i believe firmware updates rewrite the files. Ubuntu can then be booted from a supergrub2disk usb then reinstall grub. I have to work in this AM and shouldn't be up typing so one will have to research. There's plenty of info out there on these last two topics. 

Refind is awesome. There's info on this forum to get it booting from a second partition. 

For making partition look here:

https://apple.stackexchange.com/questions/364025/how-to-stop-macos-updates-from-taking-over-the-refind-boot-manager

For getting refind installed look here:

https://apple.stackexchange.com/questions/338574/bless-error-when-installing-refind