title: Custom Code Snippet not expanding on tab - this and other snippets otherwise work fine
body: <p>Found a solution: snippet shortcuts cannot have underscores in them, or they will... well, they just won't expand from intellisense.</p>
  <p>I am on Visual Studio 2022</p>
  <p>Snippets / Intellisense are otherwise working fine, if I start typing &quot;for&quot;, I get the right suggestions, and if I select one and press tab, it expands fine.</p>
  <p>I have created my first custom code snippet (just to remind me to flush stdin after using scanf_s). It has no bells or whistles, it's just to insert some text. It does not share a name with any other command, variable, snippet or anything in Intellisense (the name is just &quot;myscanf_s&quot;). I am trying it in an open .cpp file, which matches its declared language.</p>
  <p>It works in two ways, and fails in just one:</p>
  <p>A) I can choose &quot;Snippet - Insert Snippet&quot;, find it under &quot;My Code Snippets&quot;, and insert it just fine.</p>
  <p>B) It shows up as a suggestion when I type.</p>
  <p>C) But, when selecting it as a suggestion and pressing tab (or double-pressing tab, double-clicking, or ctrl-spacing), it just inserts the full shortcut name.</p>
  <p>Why is my custom snippet working so differently?</p>
  <pre><code>&lt;CodeSnippets xmlns=&quot;http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet&quot;&gt;
      &lt;CodeSnippet Format=&quot;1.0.0&quot;&gt;
          &lt;Header&gt;
              &lt;Title&gt;myscanf_s&lt;/Title&gt;
              &lt;Description&gt;Basic help for scanf_s&lt;/Description&gt;
              &lt;Shortcut&gt;myscanf_s&lt;/Shortcut&gt;
          &lt;/Header&gt;
          &lt;Snippet&gt;
              &lt;Code Language=&quot;CPP&quot;&gt;
                  &lt;![CDATA[
                  //%d is 'Dec. int', %u is 'Unsigned dec. int.', %s is 'String, %e is 'float', %c is 'single Char'
                  scanf_s(&quot;TYPE_SPECIFIER&quot;, &amp;VARIABLE, WIDTH_OF_INPUT);
                  getchar();
                  ]]&gt;
              &lt;/Code&gt;
          &lt;/Snippet&gt;
      &lt;/CodeSnippet&gt;
  &lt;/CodeSnippets&gt;```
  </code></pre>