Phone storage
Phones connected through USB cable use an obsolete MTP protocol which is not implemented in OneCommander (no documentation and severely limited protocol that can cause data loss).
In ~November 2024 Microsoft updated Phone Link app to allow wireless access to your Android phone files (not sure if iPhones have a similar app)
There's a bunch of youtube videos on this https://youtu.be/7jdcTOrk_Ro?t=77
Quick overview of steps:
On phone install Link to Windows (Microsoft's app) - version 1.2471 or newer
On PC: open Microsoft Store, Library (icon bottom left), Click Get updates (Cross device experience host has to update and Phone Link app)
Open Windows Settings and find Mobile devices
Check Allow this PC to access you mobile devices
Click Manage Devices Add device
Check Show mobile device in File Explorer
Check that your phone shows up in Windows File Explorer (through WiFi - don't connect the cable)
If it does: restart OC (close it fully with Ctrl+Close) and on next start it will show in favorites group with your name
You can also navigate to C:\Users\YOURNAME\CrossDevice and you will see your phone. You can add it to sidebar favorites for quick access.
This is completely managed by Windows. It looks like Windows synchronizes the content between phone and PC in a similar way as OneDrive, so it will show up even if phone is not Online. For any issues with phone synchronization, complain to Microsoft
Access through FTP (complicated)
If for any reason you can't use PhoneLink, there is a way to access phone through FTP, but it requires installing a few things https://groups.google.com/g/onecommander/c/igMVqW-b0Qo/m/1dqwVTY8DgAJ