Ubuntu erase disk and install option is not removing previous partitions

I am beginner. I have a new computer Asus motherboard, and WD Blue 1TB SSD. Secure Boot set to Other OS (off). Due to problems with Nvidia drivers, I tried to reinstall Ubuntu Budgie 20.04. My first installation was an encrypted LVM.

When I clicked the option to erase disk and install, for some reason instead of deleting all partitions in the previous installation, the new install created sub-partitions inside the previous root partition.

List of partitions in /dev/nvme0n1 :

free space                        1 MB
/dev/nvme0n1p1       efi        536 MB
/dev/nvme0n1p2      ext4        767 MB
/dev/nvme0n1p3    unknown    998898 MB
free space                        0 MB

Then, in a live session I manually deleted all the partitions using GParted, and then reinstalled.

When using the system I get a message:

system problem detected report

And booting into recovery mode, I get this error message:

Cannot process volume group vgubuntu-budgie
Volume group vgubuntu-budgie not found.
Cannot process volume group vgubuntu-budgie

It seems to remember the old installation since instead of using vgubuntu-budgie it created a new volume group vgubuntu–budgie

I’ve reinstalled Ubuntu many times on other systems and haven’t seen this happen before.

My questions are:

  1. Shouldn’t the erase disk and install Ubuntu option wipe out previous installations on the SSD? So why do I need to manually delete partitions/format disk?
  2. How can I cleanly install Ubuntu without any previous installs lingering in the UEFI?

Thank you for your help