I suspect your first ESP is the Windows original ESP.
I might try changing esp,boot flags to p1 & see if you can directly boot Windows from UEFI one time boot menu.
That will may break boot of Kubuntu, but once UEFI entry is created to know partuuid of ESP, that it has esp, boot flags may not be required.
UEFI uses GUID/partuuid which actually has been set to very long GUID into the ESP's gpt partition table with esp,boot flags.
But to be safe be sure to have working live installer to make repairs.
You can see where all the boot files are with Boot-Repair's report.
Please copy & paste the pastebin link to the BootInfo summary report ( do not post report), do not run the auto fix till reviewed. Use often updated ppa version with your USB installer or any working install over somewhat older ISO.
https://help.ubuntu.com/community/Boot-Repair &
https://sourceforge.net/p/boot-repair/home/Home/
In Boot-Repair's advanced mode is the choice to choose where to reinstall grub as auto option not always correct.