I had. "Είναι κάποιος." which was accepted as correct. But are both "κάποιος" and "κάποια" possible?
In my opinion it should be only one correct answer : " Αυτή είναι κάποια".
Yes, but "Ειναι κάποιος" was accepted with " Αυτή είναι κάποια". as an alternative.
Glad to be of help. You have given me so much help and advice and so many lessons, for which I am grateful.
Oddly enough "είναι κάποια" is not accepted, only αυτή είναι κάποια".
It's not odd it just means it hasn't be programmed into the acceptable answers. You should report it so it can be added. Duo knows that the courses are not perfect (with so many variables how would that be possible) but they have given us the: "Report a Problem" option. Or you can use the "Support" option (left side vertical) if you have left the page.
Edit I just noticed that "Είναι κάποια" was accepted for me and that was some time ago. Now, that is odd.