The first time I ran into this issue was Feb 2017. The case back then was closed without resolution. This week, we decided to test adding a couple of Windows 10 Pro systems to our MDM once again, but ran into the same password prompt issue. Today, I opened another case on it, and this was the official response:
Thank you for contacting Cisco Meraki Technical Support!
At the moment, we are currently experiencing issues with Windows devices receiving the password payload, where it causes the behaviour you are describing.
Our developers are currently working on a fix for this issue.
Unfortunately Support does not have an estimated timeframe for this, but I will provide an update for you as soon as I hear any.
I apologize for this inconvenience this will cause for your network and devices.
In terms of a workaround, are you able to remove the passcode payload from the test profile to make sure the devices are not constantly resetting, and become functional?
I did, in fact, remove the passcode portion from the profile, and it seemed to fix the problem for a little while, but then it started happening again... so I deleted the settings profile for our windows machines completely and this fixed the problem until I attempted to push an application to the Windows client. As soon as I added a custom app with tags matching the windows clients (ThinkPad, Test) the password looping issue returned. This was prior to even attempting to push the application.
I'm continuing to test... my next steps will be as follows:
1. uninstall the agent from the windows client
2. disconnect client from the windows "connect to work / school"
3. remove all tags from the device in the dashboard
4. remove owner from the device on the dashboard
5. delete the custom windows app from the App dashboard
6. delete the windows client from the network
7. wait 24 hours (this is important I've found in the past)
8. re-add the windows client starting with the "Connect to Work and School" step
I will report back later this week with my findings @RealBoringAdmin