There are some possible reasons why this is happening. You can find the 2 main ones below:
1. Your admin role does not allow you to edit learning page contents. This article: How do I check the permissions of all admin roles? and this one: I am an admin but I only have the "view" right for most of the content. Why is that? explain what that means and how you can have it solved.
2. The "editable by others" box was not checked when this learning page was created. During the creation of a learning page, the person responsible for it is able to check or leave the editable by others box unchecked. If this box is unchecked, only the creator of the content is able to edit it.
If you still have questions after reading this article, don't hesitate to contact us by submitting a ticket.
We're always happy to help ! :)