title: Google Tag Manager - Some Click URL shows undefined
body: <p>I have setup two user-defined variables in GTM:
  <a href="https://i.stack.imgur.com/fLVdm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fLVdm.png" alt="enter image description here"></a></p>
  
  <p>The 2nd one is the same. I just ask for another QueryKey. Here is my Trigger:
  <a href="https://i.stack.imgur.com/Gn5oQ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Gn5oQ.png" alt="enter image description here"></a></p>
  
  <p>And here my tag:
  <a href="https://i.stack.imgur.com/txydi.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/txydi.png" alt="enter image description here"></a></p>
  
  <p>The click url always looks the same. Example:
  <a href="https://example.com/test?productCodes=999.999.999&amp;culture=de-CH" rel="nofollow noreferrer">https://example.com/test?productCodes=999.999.999&amp;culture=de-CH</a></p>
  
  <p>The problem is, that I often get <strong>undefined</strong> as Event Action and <strong>(not set)</strong> as Event Label in Google Analytics:</p>
  
  <p><a href="https://i.stack.imgur.com/hV3BI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hV3BI.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/vtqul.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vtqul.png" alt="enter image description here"></a></p>
  
  <p>Is there any idea why? </p>
  
  <p>Thanks for supporting me.</p>
  
  <p>Bests,
  Yab86</p>