diff --git a/client/cypress/e2e/frontend/modules/highlights.cy.ts b/client/cypress/e2e/frontend/modules/highlights.cy.ts
index ad773ace..1ce882fe 100644
--- a/client/cypress/e2e/frontend/modules/highlights.cy.ts
+++ b/client/cypress/e2e/frontend/modules/highlights.cy.ts
@@ -66,6 +66,12 @@ const getAddHighlight = (pageType: string = 'ModuleNode') => {
       id: chapterId,
       __typename: 'ChapterNode',
     };
+  } else if (pageType === 'InstrumentNode') {
+    page = {
+      slug: instrumentSlug,
+      id: instrumentId,
+      __typename: 'InstrumentNode',
+    };
   } else {
     page = {
       id: moduleId,
@@ -373,6 +379,7 @@ describe('Highlights', () => {
     cy.wait('@AddHighlight');
     updateHighlight(highlightedText);
     cy.getByDataCy('highlight-mark').should('have.length', 1);
+    deleteHighlight();
   });
 
   it('visits an instrument and highlights some text', () => {
@@ -462,4 +469,41 @@ describe('Highlights', () => {
     addNote();
     deleteHighlight();
   });
+
+  it('visits an instrument and highlights the intro', () => {
+    const intro = '<p>Something here in the intro, right?</p>';
+    cy.mockGraphqlOps({
+      operations: {
+        ...operations,
+        AddHighlight: getAddHighlight('InstrumentNode'),
+        InstrumentQuery: {
+          instrument: {
+            title: 'My Instrument',
+            id: instrumentId,
+            slug: instrumentSlug,
+            intro,
+            highlights: [],
+            contents: [
+              {
+                type: 'text_block',
+                id: 'some-other-content-component-id',
+                value: {
+                  text: '<p>Hello my beautiful World!</p>',
+                },
+              },
+            ],
+          },
+        },
+      },
+    });
+    cy.visit(`/instrument/${instrumentSlug}`);
+    cy.wait('@InstrumentQuery');
+    cy.getByDataCy('instrument-intro').should('have.html', intro);
+    markText('instrument-intro');
+    const highlightedText = 'mething he';
+    createHighlight(highlightedText, false);
+    updateHighlight(highlightedText);
+    addNote();
+    deleteHighlight();
+  });
 });
diff --git a/client/cypress/fixtures/mocks.ts b/client/cypress/fixtures/mocks.ts
index ff72a8ab..73d23171 100644
--- a/client/cypress/fixtures/mocks.ts
+++ b/client/cypress/fixtures/mocks.ts
@@ -125,5 +125,6 @@ export default {
   }),
   HighlightNode: () => ({
     note: null,
+    contentUuid: null,
   }),
 };
diff --git a/client/src/helpers/highlight.ts b/client/src/helpers/highlight.ts
index 957c68ba..a3a0e8f7 100644
--- a/client/src/helpers/highlight.ts
+++ b/client/src/helpers/highlight.ts
@@ -253,12 +253,15 @@ export const createHighlightCurry =
       {
         update: (cache, { data }) => {
           const id = cache.identify(cacheSignature);
+          log.debug(id);
           const fragmentWithHighlights = cache.readFragment({
             id,
             fragment,
             fragmentName,
           });
+          log.debug(fragmentWithHighlights);
           const highlight = isContentHighlight ? data?.addContentHighlight?.highlight : data?.addHighlight?.highlight;
+          log.debug(highlight);
           if (highlight) {
             cache.writeFragment({
               id,
diff --git a/client/src/pages/instrument.vue b/client/src/pages/instrument.vue
index e49b2f73..236ce3da 100644
--- a/client/src/pages/instrument.vue
+++ b/client/src/pages/instrument.vue
@@ -48,6 +48,7 @@ import {
 } from '@/helpers/highlight';
 import { doUpdateHighlight } from '@/graphql/mutations';
 import highlightSidebar from '@/helpers/highlight-sidebar';
+import Mark from 'mark.js';
 
 const instrumentDiv = ref<HTMLElement | null>(null);
 const highlightIntro = ref<HTMLElement | null>(null);
@@ -122,6 +123,9 @@ const markHighlights = (highlights: HighlightNode[], element: HTMLElement) => {
 
 let contentSelectionHandler: SelectionHandlerType, introSelectionHandler: SelectionHandlerType;
 onResult(async () => {
+  /*
+   * Important reminder: onResult gets called everytime the query result changes, also on cache updates!
+   */
   const element = instrumentDiv.value;
   const intro = highlightIntro.value;
   const fragment = instrumentHighlightsFragment;
@@ -191,12 +195,16 @@ onResult(async () => {
   }
 
   if (intro !== null) {
-    const introHighlights = instrument.value.highlights.filter((h) => h.contentUuid === null);
     await nextTick();
-    markHighlights(introHighlights, intro);
+    unmark();
+    markHighlights(introHighlights.value, intro);
   }
 });
 
+const introHighlights = computed(() => {
+  return instrument.value?.highlights?.filter((h) => h.contentUuid === null) || [];
+});
+
 onUnmounted(() => {
   const element = instrumentDiv.value;
 
@@ -205,6 +213,13 @@ onUnmounted(() => {
     element.removeEventListener('mouseup', introSelectionHandler);
   }
 });
+
+const unmark = () => {
+  for (const paragraph of (highlightIntro.value as HTMLElement).children) {
+    const instance = new Mark(paragraph);
+    instance.unmark();
+  }
+};
 </script>
 
 <style scoped lang="scss">