Hi Ihor.

The heading and first lines of the table:

|-------------------+---------------+-----------------|
| NPS (~\Oslash_int pulg.) | DN (~\Oslash_int mm) | PP/PE (\Oslash_ext mm) |
|-------------------+---------------+-----------------|
| 1/8"              | DN 6          | PE 10 / PP 10   |
| 1/4"              | DN 8          | PE 12 / PP 12   |
| 3/8"              | DN 10         | PE 16 / PP 16   |


The \Oslash appears as the Unicode character ⊘ normally.


The \Oslash is not viewed as the Unicode character ⊘ with 
"org-table-header-line-mode". And the first line of the table appears in 
the heading.

https://i.ibb.co/jht3HL0/Captura.png


The \Oslash appears as the Unicode character ⊘, if using the package 
org-table-sticky-header <https://melpa.org/#/org-table-sticky-header> 
wich has the same objective, I think:

"...this package uses the header line to show the table header when it 
is out of sight."

https://i.ibb.co/T8fD3BR/Captura.png


Best regards


El 13/03/2023 a las 12:37, Ihor Radchenko escribió:
> Ypo<ypuntot@gmail.com>  writes:
>
>> When enabled org-table-header-line-mode, the LaTeX symbols in the header
>> are not fontified.
> It would help if you provided a reproducer.
>
> Note that getting this right is a bit tricky. In particular, when table
> columns are shrunk.
>
> The function doing the work is `org-table-row-get-visible-string'.
> I am wondering if there is a better way to retrieve visible string than
> what is done in the function.
>