One thing to keep in mind is that "no blackout dates" regarding SAs actually means no systemwide blackout dates. Typically that means you will be able to use SAs on $39/$49/$59 non-stop flights, but most routes, especially if a connection is required, will tend to look like they are blacked out.

I checked several short, low cost, high frequency routes that ought to have at least some SA availability on a FA blackout date, and confirmed the OP's observation that instead of each flight being marked as available or not, there is a single indication, in the (vertical) middle of the list of flights:
Back on 07-March there was a report that the web site was applying blackout dates to Standard Award booking attempts. On 23-March rove312 posted that the glitch had been resolved. It sure likes the issue has now returned.

It would be interesting to know whether CS&S is able to see any SA availability on these blackout dates; IOW, is the problem just with the web site, or is it, well, systemwide.