Why does ubuntu periodically lose access rights on connected media?

Question

Access rights

Periodically, when you connect a flash drive or portable hard drive, the ability to write to it disappears. Neither opening it with gksu nor even chmod 777 * -R medi ...... helps. When trying to change the rights through the GUI, it says "Failed to change the permissions for the object "EE39-AAA2": An error occurred while setting the rights: The file system is read-only". How to solve this problem once and for all.