castle through check??

No, but you set the puzzle up wrong - the FEN shows you forgot to give White Q-side castling privileges. 

As it is, it is the best White could hope for is Black to blunder a stalemate.

white to play & win.

It is still missing the Q-side castling rights:

3k4/8/8/8/8/1p6/pr6/R3K3 w - - 0 1

After the "w" it should read: 

3k4/8/8/8/8/1p6/pr6/R3K3 w Q - 0 1

So the puzzle is this:

i specifically checked the box allowing queenside castling priveleges 3 times.

This is still happening.  I just played a game where my opponent castled through a check. Is chess.com working on a fix for this???

Which game? I looked at your games from today and find no issues. 

I see this one in your recent games https://www.chess.com/game/live/42909032357 that you may think is wrong, but the K does not move through check so it is legal. 

Stop trolling. Post the game where it happened or shut up

very unhelpful as usual

they say the Pam-Krabbe castle WUZ legal for a short moment in time. then FIDE got winda it & made it illegal. i cant stand them.

I have been showing reconnecting mid games which really eats up lot of my time, i have a good internet connection and i have disabled any extensions for the site , so its clearly an server issue from chess.com's end , please try to fix it or i'll have to switch to some other site for chess

IT SHOULD NOT BE ILLEGAL.

Petition FIDE to change the rules of Chess

Instant block

bot castled through check!

Show the game here

Why Singapore specifically