New at this!

You double your efforts at accurately logging. Double check all the items in your food data base for accuracy, you recommit yourself to weighing accurately, you verify that your calorie burns are accurate and not just MFP over estimates and then you stick to your calorie deficit plan until you get the whoosh. It takes supreme confidence that you are doing everything as correctly as possible to go weeks without the scale moving but if you have confidence you know it will happen. Then when it does you can do some simple math and check your total calorie deficit against the weight lost in the whoosh to verify how accurate you have been logging. Find any errors and eliminate them in prep for the next stall.