Sysupgrade keep data with ext-root overlay

Ciao!
How are you?

Guys, how come after I keep all settings, I have an ext-root overlay, but after sysupgrade, my ext-root is lost.
I cannot re-use the overlay, the storage where it is /dev/sda3, it working, /dev/sda2 swap is working, but overlay is not working, I have to create a new format with mkfs.ext4 /dev/sda1. Is there and ID in it, or what is wrong I am missing?

After keep settings and sysupgrade, it should keep as it was.

I tried this:

block detect > /etc/config/fstab; sed -i s/option$'\t'enabled$'\t'\'0\'/option$'\t'enabled$'\t'\'1\'/ /etc/config/fstab; sed -i s#/mnt/sda1#/overlay# /etc/config/fstab; cat /etc/config/fstab;

uci commit
reboot && exit

The I tried this:

block detect > /etc/config/fstab; sed -i s/option$'\t'enabled$'\t'\'0\'/option$'\t'enabled$'\t'\'1\'/ /etc/config/fstab; sed -i s#/mnt/sda1#/overlay# /etc/config/fstab; cat /etc/config/fstab;

mount /dev/sda1 /mnt ; tar -C /overlay -cvf - . | tar -C /mnt -xf - ; umount /mnt

uci commit
reboot && exit

Anohter settings, not generating the overlay, I can only mkfs.ext4 /dev/sda1, then do what is before, and then it works.

How come?!?!?!?

Thanks appreciated so much!

Bye,
Patrik