Movie renders do use the game simulation by the way, so when you render the final movie it should work, though it is hard to preview.
Without knowing what blueprints nodes you are using, maybe this will work for you;
Create a float variable on your blueprint for each morph you wish to animate.
Check “Expose to Cinematics” on the variable settings (so it is editable via Sequencer).
Create a function with the name “Set” and make the function take one input of type Float
Use that incoming value and assign it to your variable.
Use the incoming value/variable and call the blueprint nodes needed to set the morph target with that value.
Now when you animate the property in Sequencer it will automatically call the Set<…> function you created and pass the evaluated value. This gives you a chance to run other code (such as setting the morph target values) as a result of the Sequencer evaluation. This should work in the editor (may require checking “Call in Editor” on the Function properties)