Odd problem with HPE smart array and sanboot

[p4rancesc0]

Hi,

I'm booting a couple of old HPE BL460G6 server with iPXE.
I'm using iPXE with MAAS and I'm stuck with the final phase of deploy where the ipxe.cfg should tell to the server to boot from le local drive.

Nothing new, I found a lot o people complaining about this and the HPE smart array controller.

But I found out really an odd behaviour:

If the ipxe script contains only:
sanboot
everyhting get stuck

But if I press control + B, enter the iPXE console, and issue the command:
sanboot
everything works like charm...

I tried with some sleep and other odd solution inside the but nothing seems to work.

Can anyone please explain to me the difference between issuing the sanboot command from a script or issuing into the interactive console ?

I'm using:

ipxe.pxe

and

undionly.kpxe

BR
Francesco

PS
it's the 3rd time I try posting... sorry in advance for eventually double or triple posting