The object names used in the Iron Speed Designer V3.0 design themes have changed from earlier versions. As a result, custom design themes will be problematic when creating pages. Specifically, copying a custom design theme from an older version of Iron Speed Designer will cause problems.
During migration, Iron Speed Designer will not update any custom design themes. Only design themes provided by Iron Speed Designer are updated.
Recreate your custom design theme using a V3.0 design theme as the “base” you modify.