Provided you have everything set up correctly, you should see something on your scope while i2cdetect scans the I2C bus for available devices.
I2C is built such that you get a NACK after writing the i2c-address if you try to talk to an address that doesn't exist on the bus. This is how i2cdetect knows a device of a specific address doesn't exist on the bus. So you can't see any actual data transactions without having another device on the bus. See the I2C User Manual.
I suggest you attach a simple I2C device such as an RTC (like DS3231M or DS3232M) or a temperature sensor on your I2C bus and try interfacing with them to see an actual I2C transaction.
Another method (which I usually use) is to have another microcontroller with a known-good I2C-slave implementation act as a loopback on the bus.