fix: i18n reversion (#860)

Author: KaneFreeman

packages/core/src/components/entry-editor/EditorInterface.tsx

@@ -4,7 +4,7 @@ import { ScrollSyncPane } from 'react-scroll-sync';
 import { EDITOR_SIZE_COMPACT } from '@staticcms/core/constants/views';
 import { summaryFormatter } from '@staticcms/core/lib/formatters';
 import useBreadcrumbs from '@staticcms/core/lib/hooks/useBreadcrumbs';
-import { getI18nInfo, hasI18n } from '@staticcms/core/lib/i18n';
+import { getI18nInfo, getPreviewEntry, hasI18n } from '@staticcms/core/lib/i18n';
 import classNames from '@staticcms/core/lib/util/classNames.util';
 import {
   getFileFromSlug,
@@ -305,6 +305,10 @@ const EditorInterface = ({
     [collection, entry, fields, fieldsErrors, handleLocaleChange, selectedLocale, submitted, t],
   );
 
+  const previewEntry = collectHasI18n
+    ? getPreviewEntry(entry, selectedLocale, defaultLocale)
+    : entry;
+
   const mobileLocaleEditor = useMemo(
     () => (
       <div
@@ -351,7 +355,7 @@ const EditorInterface = ({
         collection={collection}
         previewInFrame={previewInFrame}
         livePreviewUrlTemplate={livePreviewUrlTemplate}
-        entry={entry}
+        entry={previewEntry}
         fields={fields}
         editorSize={editorSize}
         showMobilePreview={showMobilePreview}