Using SyncVar on a generic List?

I'm making a game where the user has multiple spells, cooldowns etc. To store all these values I use generic lists. The problem however is, when for example I want to check if a cooldown exceeds server side, I can't use a [SyncVar] for lists so I'm forced to make a bunch of [SyncVar] variables.

Is there a workaround on how to do this? Because now all lists run client side which is not safe.

This is the error I get: Failure generating network code. UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)