Fusion will not recognize GUID on external drive

[toastferatu]

Recently installed Big Sur on Mac that had been running Mojave.  Discovered, too late, that a LaCie SSD external drive had one volume that is no longer supported because it uses a 32 bit encryption app.  Downloaded VMware Fusion in order to create virtual machine to re-install Mojave.  Erased and re-formatted a different external drive with GUID partition map, after first attempt to install Mojave failed as disc was originally in APFS format.  Subsequent, repeated attempts to install Mojave stalled with message that destination disc is not GUID format, although as I said, disc is now GUID partitioned.  Any suggestions on how to get past this block?

[wila]

Hi, In the installer you can open Disk Utility from the menu and blow away all of the partitioning. Obviously that means the disk is wiped and all data on it is gone.

--
Wil

[G30xFF]

So, before we get Into the nitty gritty with Terminal, try:

In Disk Utility, make sure you press ⌘-2 (show all devices). Selecting the top-level "device" of your external drive, "erase" the disk, but intentionally format it with a different partition scheme, same, MBR, with an EXFAT partition. Then, erase again, using GPT/HFS+. Finally,  convert your HFS+ partition to APFS (don't do it in one go).

See if that helps... otherwise, time to do a block-level wipe using `dd`.