Hi,

Currently, if Thread.CurrentThread.CurrentCulture set to tr-TR (can be also reproduced with az-AZ and maybe some other cultures) some tags are ignored in HtmlTextBox, but they work if typed in UpperCase. This can be reproduced with any supported tag which contains letter "i" like "div" or "li".

For example, we have two ol list but one with LI and the other one with li tags:

<ol>
  <LI>first</LI>
  <LI>second</LI>
</ol>

<ol>
  <li>first</li>
  <li>second</li>
</ol>

This is how it is rendered in PDF:

When the current thread culture is set to Turkish (tr-TR), the lowercase and uppercase conversion rules differ from English — especially for the letter "i".

• In Turkish:

  • "i".ToUpper() → İ (with a dot)

  • "I".ToLower() → ı (dotless i)

Our assumption that the Telerik HtmlTextBox internally parses and maps HTML tags by converting them to uppercase. When the Turkish culture is active, this conversion causes tag names to break, which is not a valid tag, so ordered lists fail to render.

Best regards,
Denis