I picked up a couple .96" I2C displays from fleaBay. One is by Heitec and the other Bangood and I have the same problem with both.
Using the I2C scanner sketch no I2C devices are detected if they are the only I2C devices hooked up, but if I hook up my I2C I/O expander then it finds the address of both the I/O expander and the OLED. And I can run the OLED on the ADAFruit and U8GLIB libraries just fine as long as the I/O expander is left hooked up.
Do these need pull up resistors? I don't have any 4.7K resistors on hand, I tried 10K and it didn't work, but if I hooked up the I/O expander and booted up and the display was working and then pulled power to the I/O expander the OLED will keep running, but it flickers.
What's the deal with these? Why don't they run like the I2C LCD displays and I/O expanders I've used in the past with zero issues? I found where some need pull ups, but no explanation as to why they would be needed.
Once running, they're pretty neat looking!