1- In 7.5 Designer, import the attached model into an empty project. the legacy 7.4 rest properties are displayed. 2- Go to property editor, change one of the extension properties on the procedure to a different value (eg change ext-custom:Rest Method to 'POST') 3- click off the property editor then re-select the procedure 4- The ext-custom:RestMethod has been saved over to the correct rest:Rest Method=POST value. However the other rest property ext-custom:URI does not get saved over the the new rest:uri property.