Looks like systems with older UEFI systems need an older BOOTX64.EFI file.
I found this out when trying to boot my system on an older DELL
https://bugs.centos.org/view.php?id=15522
I mounted an older CentOS (CentOS-7-x86_64-Everything-1804.iso) and it worked.
Article also mentions a patch available, so I downloaded the rpm
wget http://mirror.centos.org/centos/7/updates/x86_64/Packages/shim-x64-15-2.el7.centos.x86_64.rpm
Created a directory and extracted the contents
mkdir NEWEFI
cd NEWEFI/
rpm2cpio ../shim-x64-15-2.el7.centos.x86_64.rpm | cpio -idmv
Still didn’t work.
Will continue testing.