We noticed that if you are working on a submittal review, you cannot save it and come back to it later. You have to complete the review and provide a response if you want your markups saved. Some submittals are huge and can take several days review. The only work around right now is to download the submittal and work with it offline until you are ready to re-upload. This is not a great solution. Please provide a feature to save markups within Submittals without formally providing a response until you're ready.