Hi, “Charlie” here. The problem I was having was of my own making as I wrote a small programme to generate OSM XML data and I wasn’t setting the bounding boxes to be in round numbers of Garmin coordinates. This caused Mapsource to exhibit the same symptoms as have been reported above. I’ve no idea if the cause is the same. My suspicion at the time was that the problem related to the overview map (mkgmap doesn’t create this properly whereas, afaik, cgpsmapper does).