Why am I not getting conversions on my Device ID campaign?

If the client is after conversions, we recommend moving away from Device ID.

This product is primarily served on mobile devices, which can be difficult to track conversions on because users have to have cookies enabled on these devices. The site can be hard to view on mobile devices as well, so people aren't likely to convert on these mobile devices as a result. 

Instead, we recommend using the pixel currently placed and firing on the site to run a retargeting-only campaign and track conversion URLs on this new campaign. This new campaign will serve to an interested audience (serving to people who have been to the client's site in the past), and we will be able to bid higher on these more-qualified users when it is running as its own Site Retargeting only campaign.