I just wanted to add something here because I’ve struggled with this issue.
When I edited the file in vi initially I totally forgot how important the “indent” before the “sleep” command was and naturally the delay didn’t happen.
I subsequently edited that with the indent and I can certainly confirm that in my case the “wait” for the partition happened.
However on my HP MicroServer Gen 8 with a single SSD installed on SATA 5 it still failed with the “CANT_FIND_sda3…” error.
So now I will try the alternative solution here to install TrueNas Core and then update and see if that works.
Quite frustrating since I’m sure when I installed previous versions I didn’t pick up this error at all