"hello world" examples fails on EDA Netlist Writer stage with Unconstrained error on SYS_CLK50M field.
"reference design" - philosophers example compiles wihtout doing EDA stage.
I have used Cyclone 10 LP Nios II 'Hello World' Design which work fine without any error.(opened .par ->upgrade -> start compilation)
Try again downloading the example or create your own design by referring to below link.
Can you share image of you EDA netlist setting or your project itself.