Even the suggested selector does not work

[Christine1989]

I am having trouble with selecting an element which is just eluding me since I have a similar selector for an element nearby that works just fine.

First, the HTML, simplified as best as I thought relevant:

<div id="questionsgrid">
  <div class="k-grid-header">...</div>
  <div class="k-grid-content">
    <table role="treegrid">
      <colgroup>...</colgroup>
      <tbody role="rowgroup">
        <tr class="master-row">
          <td class="k-hierarchy-cell">...</td>
          <td onchange="function">
            <input class="k-checkbox" type="checkbox" value="true">
            <label class="k-checkbox-label">...</label>
          </td>
          // two more grid cells
        </tr>
        <tr class="detail-row" style="display: none">
          <td class="hierarchy-cell"></td>
          <td class="k-detail-cell" colspan="3">
            <textarea asp-for="Comments" type="text"  class="k-textbox inputBox k-valid" placeholder="Add Comment"</textarea>
          </td>
        </tr>
        <// remaining identical grid rows
      </tbody>
    </table>
  </div>

In the above snippet I am grabbing two different elements in my code:

cy.get('#questionsgrid input.k-checkbox').then($topMatrix_checkboxes => {
  cy.log('found the checkbox')
})

cy.get('#questionsgrid textarea.k-textbox').then($topMatrix_comments => {
  cy.log('found the textarea')
})

Notice the elements I am trying to select are nested in the table very similarly, and the selector format I am using to grab is also identical. Only the checkbox is being found. The textarea is not.

After researching I cleaned up the selectors to something more robust. For the textarea I tried:

cy.get(textarea[asp-for="Comments"]).then($topMatrix_comments => {
  cy.log('found the textarea')
})

But the textarea was still not found so I then tried to use the "suggested selector" that Cypress gives when you click on an element in its interface.

This is what I ended with:

cy.get('.k-detail-cell > .k-textbox').then($topMatrix_comments => {
  cy.log('found the textarea')
})

But it is still not finding the textbox.
"AssertionError: Timed out retrying after 4000ms. k-detail-cell > .k-textbox , but never found it."

Any ideas?