Hi Lloyd Owen,
If you cannot use Power Map to get your result, I suggest you use Bing map.
Bing Maps has had a My Places feature, which is very similar to Googles My Maps feature. The My Places feature makes it easy to import data from common spatial file formats such as KML, GeoRSS, and GPX.
Please refer to this atricle about migrating My Map from Google to Bing to get more information:
If you still want to use Power Map to get your result, I suggset you post your issue to Power Map forum:
The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.
TechNet Community Su