Hi All,
Lord O Schwa here - One of the Devs for the Halo App.
We’re keenly aware that many of you are having issues trying to Sign in the to the App, or when trying to launch the App and play Halo Wars 2.
First off, We’re sorry that this is happening and we’re working to remedy this situation the best that we can.
Crashes
The Halo App Just Crashes
This is when you Launch Halo Wars 2 an then Halo App launches and then crashes 
We’ve already made some changes on our end that should hopefully mitigate this issue for some of you that are having the Halo App crash immediately upon it being launched.
We believe that we have a problem with how were displaying Blitz Packs within the app, so we’ve made them not load immediately on that page.
If you’re experiencing this problem can you please post in this thread that your App is crashing on launch from Halo Wars 2 along with your Screen Resolution and your DPI Scaling.
Sign in Issues
We’re still investigating this issue, but we recommend that you try signing in through the Xbox App, or try restarting your machine to see if it improves. Watch here for updates to this issue.
Can you also post here that you’re experiencing the Sign-in Issue.
Again we’re sorry for these issues and working to improve them as quickly as possible.
Lord O Schwa