The breadcrumb is most likely cut out because of the limit set on it at https://github.com/xwiki/xwiki-platform/blob/b010a55b43e7d8d63739694dab8d59ba4799c9ac/xwiki-platform-core/xwiki-platform-web/xwiki-platform-web-templates/src/main/resources/templates/notification/email/macros.vm#L100

The quick fix to provide a full breadcrumb would be to remove this limit.