Auto Generate Cell IDs Inserting Spaces
Auto Generate Cell IDs adds a space to the end of IDs which are not long enough, and appears to be including internal spaces. Since cell IDs cannot contain spaces, those headers are not announced by AT when reading the table. (OS: Windows 10 on desktop PC; Acrobat Pro DC 20.012.20043; latest as of 8/30/2020).
The attached file has two identical tables (Word 365, Saved as PDF) with auto-generated header IDs. With the first, NVDA (v 2019.2) only announces the headers for Vegetable, Potassium, and Brocolli. All other headers have spaces at the end, and the IDs for % DV have a space after %. NVDA reads the second table fine with those spaces removed from the IDs.
This is not an anomaly that Acrobat Accessibility Checker or even PAC 3 catches. The tagger who does not actually check the complex table with a screen reader can submit a document to the client with a table that is unreadable.
Thanks for reporting the issue to us. I have escalated the issue to the Engineering team. We have kept it in our radar and you may see it fixing in the future releases.