Yep, still there... I did un upgrade on a system with Filevault already activated... and the option to deactivate is grayed out...Is Filevault still present in High Sierra? Or is full disk encryption more transparent now that encryption support is a part of APFS?
It is present and working fine, you just can’t go on and disable/enable yet. FileVault no longer uses CoreStorage, it’s using APFS encryption instead, so they must be still figuring out how to encrypt and decrypt an APFS volume online. Remember this is the first developer beta.It always seems to be greyed out, whether active or not, don't even think Filevault will work at all on an APFS formatted drive.