Hello pima,
Can you please share the PDF report exported from the project, screenshot of the export dialog with the parameters used and the processing log from the Console pane related to the export operation? If any information is sensible, please send the data to support@agisoft.com or via PM as a download link.
I've tried different combinations of export and source data, but every time the tiles are properly cut and their size differs greatly due to the original point cloud information.