After updating to the January 2024 Google Play system update (which is different from the January 5, 2024 security update/patch), users report not being able to access data stored in internal storage across all apps. This results in various cascading issues, like not being able to play downloaded audio/video files or take new pictures, while the Files app appears empty. Other apps refuse to work.
This sounds similar to last year’s issue that impacted devices with multiple users enabled. However, the culprit today appears to be having that Google Play system update installed.