Not sure you can do that since the chips (BME680 v BMP280) are not the same and each has a unique driver to manage it. In the post above, where I have non-sensible numbers, I used the testBMP280.py script with the chip ID changed to match the BME680. That tells me the chips and drivers are reporting and processing the readings differently because the post with good numbers uses the BME680 driver from the SkyWeather kit. I'd definitely wait to see if SDL can offer some additional insights, but it seems likely that a driver change is necessary in order for your setup to work.
I figured out why I was getting the strange output from i2cdetect. I accidentally connected the Grove connector for the watchdog timer on the SunControl board to a I2C connector on the Pi2Grover board. I moved that to the D5/D6 port and only 73 and 40 showed up in i2cdetect.
I appreciate your help Jason and Doxidad. After reviewing all of the posts, it sounds like I may have a defective board that isn’t allowing me to get past the multiplexer. I’ll do some more checks to make sure I don’t have a jumper shorted or some silliness. I may have to contact the factory to see about a replacement. Thanks, again.
I did one more test to determine if the problem could be the multiplexer on the PiWeather board. If I connect the I2C bus cable for the SunControl board to the Pi2Grover board, The INA3221 shows up in i2cdetect. If I connect it to the PiWeather board, it doesn’t. I think that is pretty good indicator that there is a problem with the PiWeather board. Hopefully, somebody from SDL can tell me how I can exchange the board.