Hi Isaac George,
Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.
Try launching a full Remote Desktop session to the server, instead of Remote App, so that we can know If it works in a full desktop session but not as a RemoteApp, the issue could be session isolation.
Some applications may not work well as Remote Apps due to their design, especially if they need unique logins or interact with system components. Test the app in a full desktop session. If it works in a full session but not as a RemoteApp, there may be compatibility issues. Check this for more information Publish applications with RemoteApp in Azure Virtual Desktop
See that you are using latest version of the AVD client. Please find the below document link for your reference: What's new in the Remote Desktop client for Windows
I recommend you please go through the below similar issue article for more information: Remote app windows like outlook in azure virtual desktop are not displaying on screen correctly
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