What version of InDesign? Exactly how did you export the PDF file? What PDF setting did you use? What application are you viewing the PDF in?
Your questions have half solved my problem for me!
I'm using the latest version of Indesign (7.5) and Illustrator (15.1.0)
I'm exporting using the High Quality Print setting (I know, a bit strange to use this setting AND want hyperlinks, but the PDF is intended for web distribution to people who might decide to print it) and when I choose anything above acrobat 4 in the compatibility drop down (5, 6, 7...) then the transparency flattener is greyed out in the advanced tab, with medium set as the default. If i want to choose my own flattener settings, I have to go with PDF 4, at which point I lose hyperlinks. I've also tried exporting choosing Adobe PDF (Interactive) from the initial menu, but that results in the same lines in the gradient mesh.
However, it turns out this issue is only happening when viewing the pdf in apple's preview app. It actually looks fine in acrobat. However, seeing as how Preview is the default app for viewing PDFs on a mac, I'm concerned that a bulk of our audience will be seeing it this way.
I know this likely puts things out of the realm of adobe, but if you have any wisdom to impart, I'd appreciate it. Attached is what the file looks like viewed acrobat (above) and preview (below).
Preview is not a good viewer for complex PDF. That's a fact of life. If you want good results, tell your viewers to use Reader. It's free.
Clearly the issue is with preview, and there's not much I can do about it. Wanted confirmation that there wasn't something I was doing wrong.
This was my first post to the Adobe forum, and I have to say I was impressed with quickness and quality of the responses. I'll be back!