You can search Penn Quarter Living for what's going on with the old Waffle Shop at 522 10th St NW. Right now, nothing. The only thing left is the 'S' from Shop part of the Waffle Shop sign.
You can still see the signage for the Help-Shop a New York City based company that set up a pop-up shop at the old Waffle Shop back in 2012. As with commercial pop-ups, they're here then they are gone.
When looking for the tax records I hit a snag. Apparently there is no 522 10th St NW. 504 10h St NW is the Lincoln Waffle House a few doors down, in the tax database it is 504-508 10th St NW( 0347 0826). Then there is 512 10th (0347 0825), various units of 514 10th owned by Ford's Theatre, then 516 10th (0347 0823) owned by the District of Columbia, 518 10th (0347 0822), and that's where the numbers end. I did find 522 10th in the DCRA PIVS. There was a permit issued in 2012. It seems that it may be part of 1000-1006 F St NW (0347 0023) around the corner, owned by "JAMEL STERLING LP & JAMEL'S UP AGAINST THE WALL LLC". Jamel's Up Against The Wall is listed as the owner of 522 10th St NW in PIVS.
You know if you just switch up the e and the a in Jamel, you have Jemal, as in Douglas Jemal. Downtown vacant commercial property in no rush it seems to be useful? Smells like Jemal. Looking at the Douglas Development site there is something in their 1000 F St NW info packet that has 10th St facing retail and something about construction starting in 2013. It's hard to say of any work is going on and it doesn't matter if it is taxed at the vacant rate or not. Commercial property taxes downtown are crazy high anyway and Jemal develops a property when he's damned well ready to and nobody can rush him or his company.