Pitch correct bug in Cbs 10.0.20

Hi, after update to Pro 10.0.20 i found that every instance of Pitch correct has troubles with input with fundamental around 50hz. It distorts several samples. Im using pitch correct unusualy as rough tuner for analogue synths, because of good usability in low freq. range. And im using it only as passing trough without any correction and on older version (6.5 artist) was completely OK - unafected sound. Now it makes thist “bit distortion” synced to fundamental frequency as You can see on picture in attachement. when I turn osc litle bit higher its OK, also it didnt appear all the time. So do You have any idea what I can do wrong? Or how to tune osc at very low frequency in cubase? I have several project with Pitch correct left in track insert that now distords my tracks.
Update: it seems that its related with project sample frequency, it occurs if its higher than 48kHz. and on 192khz its worst than on 96kHz.
Update2: Its also highly related with formant settings - so probably not issue inside of Cubase itself, but with algoritm inside Pitch Correct.