I elevated an application, but drag and drop between the elevated and other non-elevated applications isn’t working anymore. What can I try?

When PolicyPak elevates a process it also changes its Integrity level.
(Learn more about Integrity levels here: https://msdn.microsoft.com/en-us/library/bb625957.aspx)

As such a newly elevated process may not be able to communicate with a normally running process.
It’s like a Queen not wanting to talk with a commoner.

That being said, you can reduce the Integrity level of the process which is running elevated. To do it, instead of selecting “Run with elevated privileges”, choose instead “Run with customized token” like what’s seen here in these two screenshots.

This enables you to change the Integrity level. You’ll want to try Medium-High first, then fall back to Medium or Low .. stopping at the first one which works.