Inspiron 5400 AIO, Bluetooth can send but not receive?

After 10 years struggling with the dysfunctional Bluetooth on my Dell XPS one 2710 (the grandfather of all Dell AIOs) which was never resolved, imagine my horror when I bought a new Inspiron 5400 AIO that send Bluetooth files perfectly, but cannot receive them from any device. 

The message is always (from the sending device) that 'SENDING FAILED Connection unsuccessful' this despite it shows in my Inspiron 5400 AIO that my device is PAIRED and the same on the sending device!

I've run all the SupportAssist and even the Bluetooth troubleshooter which 'fixed' Bluetooth On (it was never off). No change. However, my Inspiron 5400 AIO came with Windows 11. When I run Bluetooth Troubleshooter, it identifies my Inspiron 5400 AIO as having Windows 10, not 11. Could this be the issue?

I have tried 5 devices. Three Samsung, one HTC and one OPPO (Chinese Android phone). None of them can send any file to me. All of them can receive and pair.

Help kindly.