I have a seat available on the free plan but it won't let me allocate to anyone

I have a free plan (working for a not-for-profit). I have 2 seats on the plan. One is allocated to me and the other is free (it says its available on my account). When I try to allocate it, it doesn’t allow me and pushes me to pay.

I historically had another user on the account, that account is deactivated and so therefor expected the seat to be able to be allocated to someone new. But its not working. Can anyone help?

I solved it so all good - added them as developer and then changed

Thanks for posting your solution @RB48 ! Would you like to add more detail so the community members can use your solution as well? Thanks! Victor

I followed this threat which I found after I posted - it seems to have worked - I added the additional user as a developer initially and then changed them to a core seat https://community.hubspot.com/t5/Account-Settings/Can-t-add-a-2nd-free-seat/td-p/1222891