I'm 13 years GNU/Unix and Linux user, did many things on Ubuntu, Debian, BSD, SliTaz etc.
First time on Arch, as I intended to install a small operating system with packages I choose, no livecd.
Upon first test, I did a quick update on Archinstall through pacman, just in case.
Ran Archinstall.
Problem is;
When I select the EFI partition, I can see the option on the list "Assign mountpoint" I select it, write /boot as intended.
When I select the OS partition, There's no option "Assign mountpoint".
In hopes of it asking me later I continued the installation, killed well 40 minutes of my time, and installation couldn't begin at the end, due to root folder not defined issue.

*photos of screen of correlated issues are in the attachments.
https://ibb.co/C3bJpBT1
https://ibb.co/BHxyvJgy
https://ibb.co/WqB7VkD

**sorry this is very urgent post I need my computer running asap, I couldn't find how to make images appear on forum in my limited time so I'm using ibb for image upload.
PLEASE WELP!!