Bad on output of Constant-Current source
Your circuit simulates fine in Circuit-Lab.



simulate this circuit &ndash; Schematic created using CircuitLab
The comment from vangelo on your question is also applicable - for 0V in you cannot get 4mA out with this circuit.
It's not a 0-2V to 4-20mA converter, it's a 0-2V to 0-20mA converter.