2captcha are solving arkose captchas, but you need to specify the maximum you wish to pay.
Login to 2captcha then goto
https://2captcha.com/setting#bid-limit
On the right side, you can see the price to solve 1000 captchas is $7.00, so you must specify your max bid to be greater than $7.00. As you can see, I've selected $10,99 as the maximum I am to pay.