Convert to APFS option not available or greyed out

PS,

attempting to envoke the updater after the fact (diskutil apfs convert diskXXX) results in:

Exiting conversion operations with error code -69546

Error: -69546: Conversion to APFS of a macOS system volume is only allowed in the OS Installer Environment

And a quick update. Re-installing from the recovery console with the install log showing, I see the issue; the installer (now for beta 6!) reports that it cannot convert to APFS as the volume is not HFS extended.

The problem is, it is. Tried this on 2 Mac Mini (both 1TB Fusion drives, one with Filevault, one without), and an iMac 2017 (1TB SSD); same error.

Any change bootcamp is involved?

Might need to file bugs, otherwise.

When running the logger during install, this is the 'issue':

Aug 15 15:58:53 XXX osinstallersetupd[96290]: Target is not convertible to APFS: This volume is not formatted as Mac OS Extended (Journaled).

Aug 15 15:59:55 XXX osinstallersetupd[96290]: Is solid state disk returned: -69808

Again, on all 3 systems, the disk is formatted in Mac OS Extended (Journaled) !

I think the bug is related to Core Storage on boot volumes?

The iMac runs 1TB SSD with Filevault (=CoreStorage), the 2 Mac Mini's run Apple's Fusiondrive (1TB), one with Filevault, one without! However, Fusiondrive also =Corestorage.

Does this mean beta 6 (and 5 - and previous) is still incompatible with Core Storage Volumes for conversion???

I am experiencing exactly the same bug!! Hopefully it will be addressed soon!!

Macmini 2012 with FileVault turned on and fusion drive 1tb Apple HD + Samsung 256GB SSD on beta 8-

Installed 10.13b8 and was not given the option to upgrade to APFS on install.

System worked fine under HFS after install.

Booted into recovery console and convert to APFS was greyed out. Made sure drive was unmounted still grey.

Mounted drive and ran first aid through recovery console. No errors were found but it did adjust the logical volume size at the end.

Checked again, NOW Convert to APFS was selectable.

I too have had the issue of a greyed out APFS Covert option, on two drives on a Mac Pro 2010. Both are HDD with HFS+ Journaled with Filevault turned on. I took what you said about running DiskUtility after mounting but did not see the option become available until I unmounted the volume again. Once unmounted, the option to convert to APFS was available for one of the drives, a secondary drive I use for booting with self installed utilities. That drive did convert successfully. My primary drive however failed to convert and while in recovery mode, did not want to bless as startup disk. Rebooting however brought my system back up as normal for my primary system. I know early on, APFS was not available for Mac Pro 5,1 which I believe is my model. I have not seen an update to this but will investigate further and report back sny findings. Also running into a few other unnallocated errors with APFS HDD drives I now have on my system, internal and external. Looking forward to this advance in disk format though. I'm an archiver so file moving is frequent for me.