what is lower? pressure or temperature?
i wrote a few postings ago: "the hotgas bypass will increase discharge and compressor temp"

and i would say, that this is the "normal" reaktion of the circuit.
you increase the suction gas temperature and after compressing it, it should be hotter, than compressing a gas that has a suction gas temperature of -50°C.

our discharge copper pipe was so hot, that you couldnīt realy touch it.
i donīt know the reason for that, but we used a hot gas bypass before desuperheater. and the regulation of the bypass was controlled by the sps that fully opens the mgv (which has a inner diameter of 3mm) so a lot of hotgas will flow through it at once.

you have only opened the valve a little bit and you are using gas at room temperature. so this amount of gas is also cooled by the suctin gas. so all at all your suction temp doesnīt rise a lot.