Pasting HTML Table with Mixed <th> and <td> Drops Columns

[ssigwart]

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Body

When copying an HTML that that has both <th> and <td> in the same <tr>, the <th> column is dropped. And example is below.

<table>
  <tr>
    <th>Col A</th>
    <th>Col B</th>
    <th>Col C</th>
  </tr>
  <tr>
    <th>A1</th>
    <td>B1</td>
    <td>C1</td>
  </tr>
  <tr>
    <th>A2</th>
    <td>B2</td>
    <td>C2</td>
  </tr>
</table>

Col A	Col B	Col C
A1	B1	C1
A2	B2	C2

Steps to Reproduce

1. Highlight the table above, then copy it.
2. Paste it into the text of an issue.

It winds up pasting this:

Markdown

Col A | Col B | Col C
-- | -- | --
B1 | C1
B2 | C2

Rendered

Col A	Col B	Col C
B1	C1
B2	C2

Guidelines

• I have read the above statement and can confirm my post is relevant to the GitHub feature areas Issues and/or Projects.

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[ebndev]

Hi @ssigwart, thanks for being a part of the GitHub Community!

Can you share a screen recording? I was unable to replicate the issue as the HTML did not get changed to markdown on my end.

[ssigwart]

Hi, @ebndev. Thanks for the quick response. Here's a screen recording. I typed Cmd+C to copy after highlighting. I'm not sure if it matters, but I'm on MacOS.

Screen.Recording.2026-01-23.at.11.03.38.PM.mov

[MasteraSnackin]

This appears to be a bug in GitHub's HTML-to-Markdown table converter. The issue occurs when a table has mixed <th> (header) and <td> (data) cells within the same <tr> row.

What's happening

When you paste the HTML table, GitHub's conversion pipeline is incorrectly calculating the column count. Instead of preserving all three columns (Col A, Col B, Col C), it's dropping the first column and only outputting two columns in the generated Markdown.

The resulting Markdown shows:

Col A | Col B | Col C
-- | -- | --
B1 | C1
B2 | C2

Notice that the A1 and A2 cells (from the <th> elements) are completely missing from the output.

Root cause

The HTML-to-Markdown converter appears to assume that:

• <th> elements only appear in a dedicated header row
• All subsequent rows use only <td> elements

When this assumption is violated (rows with mixed cell types), the converter miscounts columns and drops data during conversion.

Expected behavior

GitHub should convert the table to:

| Col A | Col B | Col C |
| --- | --- | --- |
| A1 | B1 | C1 |
| A2 | B2 | C2 |

This preserves all data regardless of whether cells are marked as <th> or <td>.

Workaround

Until this is fixed, you can normalize the HTML before pasting by converting all <th> cells in data rows to <td> elements, or manually edit the Markdown after pasting to add the missing column.