I was not able to repro this on latest Dev (59.0.3050.4). I tried with the CCT client test apk and choose 'Chrome dev' to test with. After I scroll and hide the bottom bar, TTS works. 
It doesn't work while the bottom bar keeps showing. (i.e. Issue 684675)

So we were able to repro with the wikipedia steps through AGSA. But, it doesn't repro from the CCT test apk for wikipedia.
Also, from AGSA it works on other sites, Ex. freep.com article.

Marking it M58 RBS for tracking purpose.

Is this a regression and blocking M58?

Apparently a regression but I don't think it should block M-58.  Moving to M-59 (as done to the similar Issue 684675).

Removing RBS because this seems to be a one-off or rare issue: I tried all the other links from the search in #1 and they all worked in CS.  Also I've seen this Wikipedia page after it's been opened and later returned to.  Also a quick test of other Wikipedia pages in CCTs seem to work.  I suspect there's some issue with the page looking like it has accessibility markup, a known issue with Wikipedia subsections.

There seem to be intermittent issues with Tap triggering in CCTs.  I need to keep checking this and see if there's a pattern, check with long-press, etc.