SEP (Symantec Endpoint Protection) for Mac displays a red X and "Virus and Spyware Protection is disabled" in client GUI.
LiveUpdate appears to run OK but definitions date displays "N/A".
If managed, the client will not check in with SEPM (SEP Manager).
/Library/Logs/DiagnosticReports/ on client file system fills with SymDaemon crash reports.
Symantec and Apple no longer support macOS 10.12 or older.
As a workaround, you may try running SEP 14.2.4815 (14.2 RU1 MP1 build 4815). This is the newest version of SEP that will run on macOS 10.12 without SymDaemon crashing. You must upgrade to at least macOS 10.13 to use any newer version of SEP up to 14.3 MP1. SEP version 14.3 RU1 and newer will require at least macOS 10.15.