Is this unexpected behavior still occurring in the workbook? As some troubleshooting steps I wonder if any of the following help resolve the issue.
+ Does removing the sheet from the dashboard and re-adding it to the view allow for the custom shapes to display as expected?
+ Does this occur in the latest version of 10.5 Tableau Desktop? 10.5.9 can be downloaded and installed from here.
Please also provide a screenshot of the unexpected behavior. This can better help our Tableau Community understand the issue and assist in a timely fashion.