TPS54240: does not regulate to 3.8V output with 5V input

We have successfully used TPS54240 on many circuits where we had higher input voltages such as 12 Volts and above. We are for the first time using this part with 5V input and we see that it is not regulating to 3.8V output. When the input voltage is increased to around 6.6 Volts or higher, it works well in the same circuit. Why is it having problems at lower input voltages ?

The links to PDF schematics and simulation results are below. Everything works on simulation but not on real circuit.

https://bipominc-my.sharepoint.com/:b:/g/personal/oguz_bipom_com/EdtQYdXTXuhDlUsjmtfcEasBKKKH6O1noSYz0T4ijGROFw?e=df1dpk

https://bipominc-my.sharepoint.com/:u:/g/personal/oguz_bipom_com/Ed84Zd1m0whHoe0n4m8iN8QBkVBXAbmy5gISMNTcvmQk0w?e=ETccCD

Any ideas ?

Thanks

Oz