I can enable and disable all protocols in Enabled Protocols dialog, but some protocols is missing from protocol preference list. They also don't available as decode options for network traffic. Why is that?
Not all protocols need preferences. If the developer of the dissector for that protocol didn't find a need to allow/make the user choose to modify the dissector's behavior in some way then s/he wouldn't create a preference for that dissector.
Similarly, not all dissectors are registered appropriately for Decode-As functionality. If you have a protocol/dissector that you'd like to use with Decode-As but it's nor currently supported then please open an enhancement request.
Note that these two things are actually independent of each other: protocols can have preferences but not be registered for Decode-As or vice-versa.
Comments
Example protocol?