this is not working in InDesign CC 2015, as far as I can tell.
Anne-Marie (yes, I see you behind that mask!), did you try the other method of setting tab order as shown in this Help file:
Namely, Objects > Interactive > Set Tab Order.
I just tested the latter in InDesign CC 2015 and it works fine.
I could never understand why you would take the trouble to drag form fields to the Articles panel when they're all listed in the Set Tab Order dialog.
And, as I just tested, it doesn't seem to get written into the PDF file in CC 2015.
OK, I investigated further. The Articles panel changes the Structure order of the PDF file.
If you choose Article Options from the Articles panel, you see this:
When you make changes in the Articles panel it does change the reading order of Tagged PDF. You can view this in Acrobat's Tags pane (in the left Navigation pane).
Open up the Tags pane, and the order you list in the Articles panel is reflected here. I had selected, out of order four text fields in a PDF form created in InDesign.
The choices I made are shown here:
This is what the Tags panel shows in Acrobat, the order I set:
The Help file is incorrect. It's mixing up form Tab Order, which is what the Tab Order dialog sets with Structure order within the PDF, which can be used to determine reading order.
But ... I was trying to get Acrobat's Tab Order of the fields to reflect the tab order in the Articles panel. I finally figured out that each form field has to be a separate article, rather than form fields within an article. That worked, and I didn't have time to investigate further.
The reason you'd use the Articles panel is that it's far easier to drag and drop than to select individual field names and use the up and down arrows. OTOH it's a major pain to drag and drop the fields over from the layout to the Articles panel in the first place! Neither solution is acceptable! argh. ;-)
I want a view that shows the Tab order numbers next to the fields, and lets me click-click-click in the order that I want, and have InDesign update the tab numbering. Then when I open it up for editing in Acro, and choose to View Tab Order Numbers, the numbers to reflect the exact same thing.
AM (not incognito, just forgot to switch to my forums login ... this is my CC login. Don't ask me why I made two!)
I agree with your idea for a better method.
But with the Set Tab Order dialog you can drag up and down. You don't have to use Up and Down arrows.