I have checked your account details and noticed that the Adobe Stock subscription under the teams account has been cancelled and that is the reason you are unable to assign the assets to any of your members.
Additionally, I can see an individual Stock subscription under your account which can't be shared with your team members and the licenses/assets can only be accessed by your Adobe ID.
Please contact our support team Support FAQ: How can I contact Adobe for support? for further assistance.
In case you are unable to reach our support team through the above-mentioned link, please see Contact Support FAQ: Unable to reach support through the "Contact US" link