diff --git a/addons/web_editor/static/src/js/backend/convert_inline.js b/addons/web_editor/static/src/js/backend/convert_inline.js
index 0889c929733..4d1745903a8 100644
--- a/addons/web_editor/static/src/js/backend/convert_inline.js
+++ b/addons/web_editor/static/src/js/backend/convert_inline.js
@@ -552,11 +552,14 @@ async function toInline($editable, cssRules, $iframe) {
     $editable.removeClass('odoo-editor-editable');
     const editable = $editable.get(0);
     const iframe = $iframe && $iframe.get(0);
+    const wysiwyg = $editable.data('wysiwyg');
     const doc = editable.ownerDocument;
-    cssRules = cssRules || doc._rulesCache;
+    cssRules = cssRules || wysiwyg && wysiwyg._rulesCache;
     if (!cssRules) {
         cssRules = getCSSRules(doc);
-        doc._rulesCache = cssRules;
+        if (wysiwyg) {
+            wysiwyg._rulesCache = cssRules;
+        }
     }
 
     // If the editable is not visible, we need to make it visible in order to
diff --git a/addons/web_editor/static/src/js/wysiwyg/wysiwyg.js b/addons/web_editor/static/src/js/wysiwyg/wysiwyg.js
index 7b609bbb685..ad8ff8eb198 100644
--- a/addons/web_editor/static/src/js/wysiwyg/wysiwyg.js
+++ b/addons/web_editor/static/src/js/wysiwyg/wysiwyg.js
@@ -2548,6 +2548,7 @@ const Wysiwyg = Widget.extend({
         }
         const {collaborationChannel} = this.options;
         this._stopPeerToPeer();
+        this._rulesCache = undefined; // Reset the cache of rules.
         // If there is no collaborationResId, the record has been deleted.
         if (!collaborationChannel || !collaborationChannel.collaborationResId) {
             this.setValue(value);