PDF Symbols Disappear when Editing in Acrobat Pro

[Kasi5C4F]

The text that's been dissapearing are the ≥  ≤  >  < (greater than, less than, greater than/equal to and less than/equal to symbols). 

I've looked online and tried to find a solution but can't seem to find anything exactyl matching what I'm doing. We get sent pdfs which we then bring into InDesign and export. We don't try to change anything in InDesign we are mostly just laying these pdfs on a template so they have a fancy header/footer.

We then export the pdf from InDesign and add links to some of the text (links to the next page, back to the beginning, to websites etc.). Often we need to edit the pdf directly in Acrobat (usually only the header/footer). Sometimes when I do this  these symbols dissapear (≥  ≤  >  < ). What's confusing is only some of them dissapear and sometimes its not on a page of the pdf I made a change to. It seems completely random. When the customer tries to edit on their end sometimes the symbols switch (≥ becomes ≤). That seems to only happen for them. I've also tried to replicate an error like this and it doesn't always work the same way. Something else could cause the symbol to dissapear while what caused it to dissapear last time doesn't.

Additionally a file may look good both our ends but then loses a symbol when they upload the file to their website.

Let me know if anyone has an idea of why this may be happening, thanks!

[gary_sc]

Hi Kasi,

I've heard of things like this happening but in that case it was the "n" dash ("–"). There is a bug somewhere between the font, InDesign, and Acrobat. Last I heard everyone was busy pointing fingers.

One temporary solution might be to just substitute a different font that's "close enough."

I've been using computers long enough that sometimes it's better to get the job done than trying to get the job done the way it's supposed to work!

Please update on what font was being used and if an alternate font works what that font is. 

Thanks!

[Kasi5C4F]

The font being used is Calibri - I believe the symbols may be from the glyph selection. It seems like it should work since it's such a common font. I was thinking of suggesting Arial to them - do you think that would work better?

Thank you so much!

[gary_sc]

IF (and I really do not know if it is) IF this is the same issue as I've seen elsewhere, it's a bug in Acrobat, not the font. 

I can only suggest that you try Arial and see if it works.

[Kasi5C4F]

Thank you so much, I'll give that a try!

[Bevi Chagnon - PubCom.com]

Often we need to edit the pdf directly in Acrobat (usually only the header/footer). Sometimes when I do this  these symbols dissapear (≥  ≤  >  < ).

By @Kasi5C4F

Sometimes when you edit PDFs in Acrobat, rather than in the source program like InDesign or Word, you'll lose characters. They can disappear randomly and on random pages.

Some things that can cause this:
 

1.  The PDF is tagged. Tagged PDFs can't be edited at all. They loose their content.
    
2. The font wasn't embedded into the PDF at the time it was exported from its source document. Make sure this option is checked in your export options.
    
3. The font can't be embedded into the PDF because it has restrictions on its use. Check the font's properties and ensure it has "embeddable" or "editing embedable" in its description.
    
4. Those glyphs aren't available on the font you've chosen. Calibri doesn't have a wide range of STEM characters and doesn't have any of the folowing glyphs.
   Less than / Greater than symbols in Unicode: U+2264 and U+2265.
   Preceeds / Succeeds symbols: U+227A  and U+227B (they look similar to the tradition <> symbols, but are different).
   Wikipedia has an excellent webpage on math symbols https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode

Try using a better font with more math symbols, such as Noto Sans Math at https://fonts.google.com/?query=noto  or Arial Unicide MS (an advanced form of Arial that shipps with some Windows programs).

[Kasi5C4F]

Thank you, I'll take a look at that!

[Brad @ Roaring Mouse]

This can be due to diffrences in encoding between the version of Calibri used by the author/program when the PDF was created, and the version YOU have when you are doing edits. As soon as you try to edit with your version, all of the special symbols are no longer valid for that encoding and will change to something else, gibberish, or nothing at all.

(If you opened one of the existing PDFs in Illustrator, you can see what hell an encoding mismatch can cause).