I've run into a dead end investigating the following issue:
Some of our engineers have reported that occasionally when they export DGN files to DWG some of the converted DWG files come out empty. This issue seems to only affect direct attachments of the main file. This behavior happens in CONNECT Update 15 and 16. In SS10 it exports with no issues.
I've sent the following sample project to Bentley so they can further investigate. I think it may have something to do with how Microstation handles nested references during DWG Export. Here is the ZIP file:
It contains a basic folder structure and several DGN files which are referenced to each other. Extract the ZIP to an empty folder. Then load main.dgn and export it to DWG. Make sure to set "External References" to "Retain" and toggle on "Convert Reference Files". Then check if exported reference SR-2865.dwg has any content.
Please note this issue is being investigate by MicroStation tech support in Service Request: 7001279327 but it would be interesting to also have testing from the user base.
RegardsAndrew BellTechnical SupportBentley Systems