Exchange 2016 on premise - remove sync devices older than 30 days

Hi guys, 

I am trying to run a command in exchange PowerShell to remove active sync devices older than 30 days from our on premise Exchange 2016 server. 

I am using the below command:

Get-MobileDevice -result unlimited| Get-MobileDeviceStatistics| where {$_.LastSuccessSync -lt (Get-Date).AddDays(-30)}

However, when I run this, it seems to just sit there and get stuck and not run anything. I have tried to leave overnight but still nothing. We only have around 150 devices to remove, so not a massive amount.

Any ideas to why this isn't working/other scripts to run?

Any help appreciated.

Thanks