And old problem with Colorado and Canyon with immobilizer (no start sometimes)

It has been a while for me on this forum. I have an old problem. Since it only happens about every 3 months, I usually just forget about it. My 2007 GMC Canyon just sometimes does not start. It turns over, no start. This is a common problem with GM vehicles it seems. If I get in the vehicle and the red lock light (immobilizer) is blinking, the truck will not start. If I wait about 5 minutes, the light is then on with no blink and it starts. The problem is everyone seems to have a different fix for this. Such as, re-flash computer, replace plastic reader at end of ignition switch, live with it. Any experience or ideas on this one? Most times it is not a big issue, but one of these days it will happen at a bad place. Oh, my keys are all solid with no transponders. My son thinks maybe the previous owner put a transponder key under the plastic trim so any key will work. Any help for me?

Seems to be very common on this vehicule if you read all the complaints.

Thanks for the reply. I am hoping someone says, “yep, had this problem and this is how to fix it.”
I have heard many possible repairs, but too many are different so I am not sure what to do first. I hate to just keep throwing parts at it. Other than this, pretty good vehicle. Runs good, and not a bad ride.