Hey, I'm going to post this to some threads specific to the Damage Calculator, but it is not functioning at the moment. Multiple people in the AG chatroom have confirmed this as well. You can't select any Pokémon/abilities/items/anything on it right now.
Edit: It appears some users are able to still use the Damage Calculator, and some are not able to use it. Apologies for misrepresenting the problem at first. I'm investigating what I can right now.
Additional Edit: This is what I could determine. For me, I cannot select any Pokémon in the Sword and Shield part of the Damage Calculator. All other Gens appear to be fine for me to select Pokémon, but in terms of generating damage calculations, it is coming up with a "Loading ??? - ???" message where each calc would normally be. Additionally, I'm not sure if this is related, but if I switch between an older Gen and the S/S current Gen calcs, in S/S it shows a much smaller text box where I would be able to manually type in a set (as opposed to just select a set from the scroll-down menu options). Unfortunately, my coding knowledge is not extensive, so I certainly won't guess as to what the issue could be. I do know that I'm not alone in experiencing this issue though.
For additional information to hopefully help resolve this issue...
-I'm using Safari as a browser (as was another user who confirmed experiencing this same issue), but a few other users have reached out to me saying that they have used the Damage Calculator on Safari successfully soon after I posted this message here.
-I have had no other known issues with my Safari browser recently or today.
-I'm on a Mac computer.
Feel free to reach out to me if you have additional questions that might help with resolving this.