When didAddMarker is called my framerect is changed to all zeros. What could be causing this?

I have a scrollingview with two rulers both set to a custom ruler unit. The rulers draw, scroll and zoom with the correct spacing and tick marks. but when I attempt to add a marker to the horizontal ruler the client view goes blank.

My delegate methods are in the client vew code. When didAddMarker is called, the client view has changed to width and height of 0.

I can reset the view frame and bounds as the first line in didAddMarker but, but I don't think that should be required.

Any ideas on what could be causing the frame to be cleared?