I came across an issue where the parameters applied to a new tuned profile were misinterpreted by tuned and incorrect characters were written to grub.conf. For instance, it added spaces between the CPU core numbers and enclosed it in square brackets, much in line with a JSON string format (which GRUB2 didn't seem to enjoy)
# mkdir /etc/tuned/myprofile
# vim /etc/tuned/myprofile/tuned.conf
# cat /etc/tuned/myprofile/tuned.conf
[bootloader]
cmdline=isolcpus=2,4,6,8
# tunedadm profile myprofile
# grep isol /boot/grub2/grub.cfg
set tuned_params="['isolcpus=2', '4', '6', '8']"
This was easily resolved by enclosing the parameters in double quotes
# vim /etc/tuned/myprofile/tuned.conf
# cat /etc/tuned/myprofile/tuned.conf
[bootloader]
cmdline="isolcpus=2,4,6,8"
# tunedadm profile myprofile
# grep isol /boot/grub2/grub.cfg
set tuned_params="isolcpus=2,4,6,8"