Text object not tagged

This is killing me.

I have a table with text in cells. The text is tagged correctly in InDesign. In all other tables in the document it is tagged fine in Adobe PDF. But I have one page that keeps telline me that the 'text object is not tagged' in PAC 3.

I've checked in InDesign for invisible text, initiated the pre flight panel in Adobe and I can't fix.

Please can someone give me some guidance? 

Thanks.