Try Switching off UEFI and change to 'Compatibility" mode in the BIOS to see if it helps.(This may slow the boot of Windows unfortunately)
If not try this link which may help.
https://help.ubuntu.com/community/UEFI
Good luck and ask for more help if necessary
Persistence is saved in a file or partition named casper-rw, a persistent home file or partition named home-rw is also possible. A persistent install will save data, program installs, customized desktops, just about everything except some drivers which are loaded before the persistence file is read during boot, (NVidia graphics).
In a syslinux type install, (SDC, Unetbootin, Universal, Rufus, etc), the system resides in the root of the drive as does the casper-rw file. The filesystem for this partition is FAT32 thus maximum size for the persistence file is 4GB.
Prior to 14.04 syslinux type installs could also use a persistent casper-rw and home-rw partition. Persistent partitions no longer work except with grub2 type installs, (mkusb and the original MultiBootUSB).
Mkusb is easy to use, safe, versatile and will make a persistent partition of whatever size you want, it will then use remaining disk space to make a NTFS partition that is visible to both Linux and Windows.
Limitations, well you don't want to unplug a persistent pendrive while data is being written to persistence, luckily mkusb comes with persistence backup tools.
Best Answer
Install Ubuntu from a Pre-built Image File.
This is another version of sudodus answer in step by step format.
If working in Windows:
Download Image File:
dd_unb_ubuntu-20.04_15GB_2020-06-26.img.xzfrom mkusb Index of /isos/linux-tools/uefi-n-bios at https://phillw.net/isos/linux-tools/uefi-n-bios/?C=M;O=D Download Link: https://phillw.net/isos/linux-tools/uefi-n-bios/dd_unb_ubuntu-20.04_15GB_2020-06-26.img.xz Link to MD5SUM's: https://phillw.net/isos/linux-tools/uefi-n-bios/md5sum.txt.ascDownload Rufus*: https://github.com/pbatard/rufus/releases/download/v3.11/rufus-3.11.exe
Etcher may also be used to flash the image: https://www.balena.io/etcher/
Double click Rufus .exe file.
Select USB drive as Target drive in Rufus.
Select above Image File in Rufus.
Click Rufus start button.
Wait for flashing to complete... Done.
Password is "changeme", change it
The USB drive should boot on almost any modern X86-64 computer.
Thanks to sudodus for the image file.
In Windows it may be necessary to install 7Zip before proceeding. Rufus and Etcher will use it when working with the .xz image: https://www.7-zip.org/a/7z1900-x64.exe
If working in Ubuntu: you can use mkusb, Disks or Etcher to flash the USB drive. If using mkusb, select option "c" Cloning iso file... for flashing the image to disk. P7zip may be needed to extract the .xz image with Disks or Etcher.