Always refresh the disguise. Some plugins like to set the entities health.

src/me/libraryaddict/disguise/disguisetypes/Disguise.java

@@ -399,12 +399,9 @@ public abstract class Disguise {
                     DisguiseUtilities.removeSelfDisguise((Player) getEntity());
                 }
 
-                // If the entity is not dead
-                if (getEntity().isValid()) {
                 // Better refresh the entity to undisguise it
                 DisguiseUtilities.refreshTrackers((TargetedDisguise) this);
             }
-            }
         } else {
             // Loop through the disguises because it could be used with a unknown entity id.
             Iterator<UUID> itel = disguises.keySet().iterator();