Where can a defendant be prosecuted for failure to act - in this case failing to file a report with a state agency?

I am having a hard time determining where any element of the offense took place. I looked at CCP 13.19 (where venue cannot be determined), but according to the cases it is to be used when there are factual uncertainties rather than legal uncertainties.

That's an interesting one. I'd say it was where the defendant was when they should've made the report. Where did the defendant learn about it, where did she spend her time (live, work) when she should've been reporting it?

If I live in Dallas but am required to report on activities taking place in Tarrant, then Tarrant would be the choice between those two. But if I am required to report on those activities occurring in Tarrant to a state agency in Travis, I suppose that is where it gets confusing. If the charge is that I failed to report the activities to X located in Travis it sounds like a Travis County offense.
But I am just a civil lawyer, give a computer contract to review.

Venue could depend on where, and with what agency, the report should be filed. The Travis Co. CA and DA offices have jurisdiction over many public integrity-related offenses because of paperwork that is to be filed with agencies (Ethics Commission, etc.) located in Austin.