Apple FileVault cannot be used if the Whole Disk Encryption (WDE) drivers are installed. There are known incompatibilities with the WDE kernel extensions when using FileVault.
Warning: When installing Symantec Encryption Desktop the Whole Disk Encryption drivers are installed by default and need to be disabled if FileVault will be used after Encryption Desktop is installed.
Apple FileVault is not compatible with the Whole Disk Encryption kernel extensions.
There are multiple related issues when using FileVault while the Whole Disk driver is enabled.
Symantec Encryption Desktop has built in functionality to detect if Core Storage Volumes are enabled (which are used with FileVault) on the OSX boot volume. In this case the Whole Disk Encryption drivers will not be installed to prevent compatibility issues.
Warning: There are no checks that would prevent you from installing FileVault after Symantec Encryption Desktop (including WDE drivers) is already installed. If you try to create a FileVault volume with installed WDE drivers the creation will fail or unexpected issues might occur.
Apple FileVault and Symantec Encryption Desktop with Whole Disk Encryption drivers enabled.