What aspect ratio for Instagram?

Dear community members,

I've been trying to post my animations on Instagram lately. However, everytime I did so Instagram cropped my videos. I believe this is due to the aspect ratio.

Now, this is quite a recent issue, since I've been able to post normally before. But last month or so Instagram had this new update, which seems to support only 1:1 aspect ratios (squares videos), no other ratios are supported for some reason.

So, I tried looking for the 1:1 ratio in Media Encoder, but I can't find it anywhere, there is only the 16:9 ratio, which I know was supported by Instagram until this update.

Could anyone please help and tell me how I can put my animations in 1:1 aspect ratio (perhaps it can be done in Media Encoder but I might've overlooked it)?

If this isn't the solution, could you please tell me what is?

Thanks in advance!

Cheers.