Yes, but I'm following your instructions for how to integrate additional tracking URLs in the PowerPress plugin. If the tracking URL isn't being properly inserted into the RSS enclosure by the PowerPress plugin, then it would be a PowerPress problem.
I've sent them an email, but of course they're going to ask if I've inserted the code into the RSS enclosure. Since that is handled automatically by PowerPress, I have no idea how to verify if it's happening.