Toggling Instance Editable state of level blueprint variable does not update exposed parameters

[husberg-disguise]

Steps to repro:

• Open an existing UE project with exposed parameters
• Toggle Instance Editable state of an existing variable and exit UE without modifying anything else
• Note that nothing changed in asset in d3 or in renderstream JSON
• Reopen UE project and explicitly save the project
• Note that asset and JSON changed to reflect previous change