Hi J_a_c_k_34,
We appreciate you reaching out to us.
We’d like to gather additional details that may help us be in a better position to assist you.
Have you had the chance to restart your? Restart your iPad - Apple Support
Are you experiencing the issue on multiple external storage devices?
Also, are you using an external storage that supply its own power?
As mentioned in the article below, "external hard drives often require an external power source when used with iPad. If an external hard drive doesn’t supply its own power, and your iPad has a USB-C or Thunderbolt / USB 4 connector, you can use a powered USB hub. If your iPad has a Lightning connector, you can use the Lightning to USB 3 Camera Adapter connected to a USB power adapter."
If you are using the same steps in the article below, please check if your external storage is full.
Connect external storage devices to iPad - Apple Support
If you need further assistance, please get back to us with answers to our questions.
Those details may provide us with some insights.
Take care!