Pycharm colnsole code completion in debugger

Pycharm python console debugger (while sitting in a breakpoint) works extremely strange:

1) When I type "obj.", appears list of suggestion, but it dissapears after one second. But if I backspace and type "." second time, it works ok.

2) When I see suggestion list and start typing, this list dissapears, even if there still matching variants for completion.

Why do such strange issiues might appear?