Cached tiles not showing up properly

I have a flex map, build on the flex viewer 3.6, and I have a Lidar basemap in the map switcher. The lidar basemap is a cached tile service, with the scales set to ArcGIS online. 80 to 90% of the tiles show, but there are always missing tiles / holes at random places. They just show up as white squares on the map.

I have confirmed that 100% of the tiles are complete, and all tiles show when I bring the service into the javascript viewer on arcgis online.

Here is my app. The lidar layer is a secured service layer.

www.oregongeology.org/slido


Thanks for any help or advice in advance.

Rudie Watzig