If I understand your issue, then I was experiencing the same. And workied round it thus:
Add the Sender as an owner of the Flow
Go to the flow and in "Connections", (top right) > see all. Find the "Approvals" connection, which will have your name against it (or the name of the person who originally created the Flow), and delete it.
Log into Flow as the Sender (presumably you have permissions to do this).
Edit the flow go to the "Approvals" item in the Flow. Click on ... and go to My Connections and add a connection.
Repeat this for each Approval itme