Trap settings?

On behalf of Adobe, I'll repeat what others have told you — trapping is the printer's responsibility.

For many RIPs, trapping occurs within the RIP itself (i.e., “in-RIP trapping”) and sometimes, for digital printing (toner, inkjet, etc.) the trapping occurs in the actual imaging engine. There are very important technical reasons why this is preferred especially when you get into issues of transparency and color management.

In fact, you could cause more harm than good trying to manually trap artwork. Thus, InDesign does not support trapping in its PDF export.

For legacy reasons with older PostScript RIPs, InDesign (and Acrobat and Illustrator) does support trapping as an option as an alternative to PostScript in-RIP Trapping (not a standard feature of PostScript). Printing to PostScript to obtain a trapped PDF file is strongly discouraged since you end up with a retrograde PDF file with no live transparency, no color management, etc.

We also strongly discourage any workflows in which text is “outlined” for any number of reasons discussed numerous times on these forums.

Bottom line – if you have content for which trapping is really necessary, you should find a print service provider who has the workflow that properly supports same. This is typically not the corner quick print shop or any of the super cheapo web-services that gang print your content with that of dozens of other customers.

          - Dov

I'm not sure if this relates to your problem, but it looks like InDesign's (and maybe Acrobat's) built-in trapping has a problem with gradient's applied to text. So, you can print a postscript file using Output>In-RIP Separations and distill an InDesign file that includes traps. 

Here's what happens with text filled with a gradient using InDesign's trapping defaults—I'm setting small text so we can see the traps—seems like a bug:

If I convert the text to outlines the trapping works as expected:

Trapping really is the printer's responsibility, but if they can't solve the problem you could try converting the text to outlines either in InDesign or in the exported PDF

InDesign's built in trapping only works when printing directly from InDesign–you can't export a trapped document. AcrobatPro works the same way Acrobat's trap settings are applied when the document is printed, so even if you wanted to control trapping from your end you couldn't do it via a PDF export.

Looking at your photo it looks more like a white stroke than a missing trap—the white outline around "YOGA" is too consistent to be a trapping problem. Can you share the PDF that was sent to the printer?

You should leave trapping to the printer. If you deliver a PDF this will be done in RIP by the printer. That said: it looks like your black is a Rich Black, not only K. In that case keep away kicks in, or at least it should. I see this as the printers fault, not yours. Ask for a reprint.