When you try to import OS in MDT Workbench you receive an error: Unable to load DLL “wimgapi.dll” the specified module could not be found (Exception 0X800700E7)
After you installed Windows AIK you’ll find wimgapi.dll is located in C:\Program Files\Windows AIK\Tools\x86
Copy the wimgapi.dll file to this location C:\Windows\System32. Then everything works fine as expected.
Hope this helps!!!