I had the same issue with the following setup:
EXT4+ GRUB + LUKS
After some back and forth, i was successful with a way that Grok helped me with:
“Forcing LUKS1”
- As soon as you are in CachyOS live ISO, open the terminal and:
2) sudo nano /etc/calamares/modules/partition.conf
-
Replace every luks2 with luks1 (should be 3-4) ; save & exit.
-
Start Calamares - pick “Erase disk”, set a password for Encryption, Bootloader GRUB
-
Complete the installation and boot into the system.
There is also a way to chroot into your system after a regular install and encrypt it.