Hey @kdx -- thanks for posting! If you are uploading images via URL, please note they must be from a public location or they won't display properly. If you are using Google Drive links they must be public links. Alternatively, you can upload the images directly to Lucidchart. 

Hope this helps clarify!

Great hack as all the folders and documents in google drive we use in a company are only “shared with special people”. So we need to add images directly to lucid in case we have to export the diagramms.