Hi Steven,
In the Azure portal, please navigate to your subscription, next click on Access control (IAM) blade, and then click on View my access button.
When the assignments window opens on right, please make sure you have Owner without any conditions. The way you know there aren't any conditions is it will just have Add for the Condition column. Please see screenshot below:
If you do not see Owner in the list of assignments, then you must take action immediately. You need to assign your account Owner role to the subscription. If you already have Owner role then you can skip down to "Assigning other Classic admins Owner role to subscription" below.
Assigning your account Owner role to subscription
To assign your account Owner role to the subscription, again navigate to the subscription -- Access control (IAM) blade, next click on Add -- Add role assignment at top. Click on Privileged administrator roles tab, next select Owner, click Next, click Select members and select your account, Next, on Conditions tab select Allow user to assign all roles (highly privileged), Next, click Review + assign button and click Review + assign button again to save.
Once it has finished adding the role assignment please perform View my access step again and verify that Owner is listed without conditions as described above.
Assigning other Classic admins Owner role to subscription
After you have made sure that your account has Owner role on your subscription, you should check to see if there are other classic administrator accounts and assign them Owner role if needed. To do this, again navigate to the subscription -- Access control (IAM) blade, and then click on Classic administrators tab.
To the right of each account that still needs full access to resources in the subscription, click on Assign RBAC role, and when window pops up click on Review + assign to add the role assignment. You should see a message saying that it successfully added the role assignment followed by another message saying it removed classic administrator.
Please see screenshot below for example (it shows Server administrator, you may see entries for Co-administrators as well):
Repeat the process for each account that still needs full access to resources in the subscription.
Please let me know if you have any questions and/or something isn't clear.
Please click Accept Answer and upvote if the above was helpful.
Thanks.
-TP