Been managing for a few years, here are a few things you should consider when trying new updates/installs.
Always try installing the update manually on one of your test devices first to make sure things install as expected first outside of WMS. Then you can try it pushing it via WMS app policy. This way you can rule out issues outside of WMS.
Side note with manual installs: It’s important to know that some software has issues with the Z:\ temp environment variable. It can sometimes help to modify that variable temporarily during testing. (IE: C:\Temp, etc) However, this does not matter when using WMS to push updates to a device.
As for WMS install issues, there are plenty of log files generated within Wyse folders to help you understand what is happening. You can check system event logs as well to help you figure out install issues. A device in the system configuration screen just means its doing its thing so let it try to complete or wait for it to fail. You can add an Install Timeout in the app policy for that install for like 30 minutes to control how long WMS should wait before it cancels the install. Default is 60 minutes if left blank.
If all else fails, reach out to Dell support. They can be hit or miss but if you have pro support they will at least try their best to make sure they get a solution to issues.