OLED 128 x 32 SSD1306 display problem (picture inside)
Taking a guess in lieu of more information (see my comments above). It does look suspiciously like what is drawn is 1/8th of the screen. The controller says that it operates at 8 bits per pixel (256 monochrome levels). Are you drawing into the screen as if it was a 1 bit per pixel screen instead of 8? As I noted in the comment above,  you will not be able to hold a frame buffer at 8 bpp and still have any RAM left to do anything else.