Two major FileVault issues exist with Catalina at present. The first one has been ongoing; it will rear its head if you have multiple FileVault-enabled Catalina drives, as will be the case if you're also beta-testing Carbon Copy Cloner. When booting from one Catalina drive (doesn't matter if internal or external), only the System volume of the other one will auto-mount. This is not apparent if you're only looking at the display in Finder, you can see it in Disk Utility. Manually mounting the Data volume will work. However, if you then unmount the System volume (as CCC will do after applying a system update), you're subject to a kernel panic.The second one has been introduced in DP6. Now FileVault cannot be enabled at all on an external ⚠ drive that has a Catalina installation. When booted from the external drive, an attempt to turn on FileVault will throw an error, that blames your configuration in Security & Privacy>Privacy>Files and Folders. This message appears to be nonsense. Note that this pertains only to enabling FileVault in the first place, not to a drive that is already encrypted (which is simply subject to Issue #1.)As a topper on the second issue with DP6, when booted from the external drive, the boot device displays in Finder not as a "drive", but as a generic file icon.I have, of course, filed both issues with Feedback. Just giving a heads-up here. :-)