If "cartesian_tvalid" is not always 1, both "dout_tdata_imag" and "dout_tdata_real" are always zero.
The "tvalid" behaves correctly.
What can cause this problem?
This issue only occurs on CORDIC v6.0.
CORDIC v5.0 did not have this problem and behaved correctly.
The available work-around is to expose "aresetn" and "aclken" and then connect both of them to boolean 1.
A fix is expected in a future revision of the tools.