How to format a disk with 2 APFS containers with Disk Utility

Question

I have a MacBook Pro running High Sierra with an internal disk made of 2 volumes HFS+, case sensitive and encrypted:

I would like to switch to 2 APFS containers, case sensitive and encrypted. I am able to erase the internal disk and create the 1st APFS container + volume with no problem. Next with the Partition button I am able to add a second APFS container + volume, but the creation process is never terminating. And Disk Utility blocks here. I had to exit Disk Utility with ⌘+⌥+esc and killing it. There isn't the smallest message about any kind of error within /var/log/system.log.

Then nothing works within Disk Utiity even with an untouched external disk.

Is this a known problem with the APFS file system or with Disk Utility?

What is the correct way to create a partition made of 2 APFS containers (with of course each one one volume )?

[ The case sensitivity and encryption of FS are out of the subject here. I just specified it to give an accurate description of an actual problem to fix. Moreover, the use of these 2 functions is useful and mandatory for my work. ]

Answer 1

tbh, I'd avoid APFS on High Sierra. It wasn't yet mature.
It forces the boot drive into APFS from HFS+ at initial install [though you are often better formatting it back again afterwards.] Mojave is the oldest OS I'd use APFS for.

I also would completely avoid case-sensitive drives on Mac. It can in theory handle them, but it doesn't like them; they can cause issues.

If you do want to add a second APFS volume, you just add it as a volume to the existing Container, not as a new partition. That way the volume 'borders' are soft. If you insist on a partition you will generate a new Container, and the sizes will remain fixed - the same as HFS [or any other older format, FAT, NTFS etc.] thus losing part of the advantage of APFS.