WARNING: Currently this is broken, issue reported to Seagate.
1 – Download Seachest Lite from here.
2 – Open Computer Management and delete the existing partition on the drive you want to convert from 512 to 4KN Advanced Format
3 – Open a command prompt with Admin rights, and run the seachest lite with the following command to identify the drives:
4 – Run
SeaChest_Lite_x64_windows.exe -d PD2 --showSupportedFormats on your target disk to confirm its running with 512
5 – Run the following command to switch to 4096
SeaChest_Lite_x64_windows.exe -d PD2 --setSectorSize 4096 --confirm this-will-erase-data
6 – Wait for a few minutes for it to finish, and shut down your PC afterwards (reboot likely also work)
7 – ISSUE: Open computer management again, and the drive comes back with a corrupted partition, which is not possible to remove:
Reported issue to Seagate under here.
EDIT: As I reported on Github, there is a workaround. Right after deleting the existing partition on step 2, you can convert the disk to MBR:
This allowed me to proceed (computer still froze first time I tried to convert back to GPT, but after all, success!