I have continued to publish and never have I been instructed to make the papers be open access. No one is enforcing that mandate. The research I've been a part of is wholly funded by the taxpayer and papers that I published after the mandate continue to not be freely available.
Umm...not sure what to tell you about that, other than you’re potentially out of compliance with the terms you and your institution agreed to.
I think there is a 6-12 month “exclusivity” period still, and some journals handle that automatically if you acknowledge federal funding. For example, Current Biology moved our stuff out from behind the paywall automatically on its publication anniversary.
I’m not sure if anyone has been sanctioned for not following these, but NIH progress reports/renewals require a PMCID for any papers you want to claim. You want to claim a lot on these to demonstrate productivity, so....there’s a good incentive to do this.
From 2013 onward, the results of all federally-funded research needs to be publicly available. Here's the memo mandating it: https://obamawhitehouse.archives.gov/blog/2013/02/22/expandi...
People do generally take this seriously and there are consequences (e.g., can't use publications in NIH grants if they haven't been deposited).