Hi there thanks for posting in the community! Just to confirm do you have any non-ERD shapes that are connected with ERD lines in your document? If that is the case replacing all basic shapes with ERD shapes should resolve the issue. For more information on ERD diagrams please take a look at our ERD article from the Lucidchart Help Center.

If that doesn't resolve the issue would you mind filling out this form to submit a support ticket and including the document URL so we can take a closer look?

Please me know if you have any questions. Thanks!