How can a logic packed array be driven to X (don't care) from within a uvm sequence?

In reply to Brass:

There is not enough information to know what might be going wrong. You need to make sure all the variables that this variable goes through are also 4-state (i.e. drier and interface).

Also you could have just written

dut_bus_connection  = 'x;

without using a foreach loop.