Where is the SD card plugged in?

What is your question?

On rare occasions, but averaging at least once a month, when our Equinox is cranked up, we have no GPS available, we cannot control the radio (volume or station selection), and the air/heat cannot be controlled. An error message appears on the data screen behind the steering wheel, stating "The SD card has been removed." We pull over, turn off the engine and wait for a minute or two and crank the vehicle again. Most of the time, this resolves the trouble. We have taken it to the dealer's service department twice, but they could not recreate the problem, and were unable to do anything. Otherwise, our Equinox has been wonderful!

What makes this problem better or worse?

Nothing. It seems to be totally random

How long has your 2019 Chevrolet Equinox had this problem?

Almost since the car was purchased new