While driving my Volvo s80t6 in heavy traffic, I encountered a red light and my car suddenly shut off. I attempted to restart it, but it seemed to be running normally with no unusual sounds or issues. However, it shut off once again, as if it had gone to sleep. On my third attempt to start the car, all I heard was a single click. Although the cabin still had power and all features such as the radio and air conditioning were working, I was unable to get the engine to turn over. Even when using the key fob and starting ignition method typically required for my 2009 Volvo s80t6 model, there was no indication of any issues with the immobilizer. This car has been well-maintained and recently serviced, including a check of all seals and servicing of the turbo at 10K miles. The tires and brakes are also new and there are no signs of any leaks as evidenced by placing cardboard under the vehicle. Prior to its unexpected shutdown, the car had been running perfectly without any warning lights or problems.

Has anyone ever experienced anything similar

 

If you haven't already done so , check all the fuses and connectors for the battery alternator and anything else.
My car was running fine too until I left it for 5 minutes and came back to a crank no start... I chased my tail for over a week just to find a burned out fuse under the hood.
I hope you find your problem if you haven't already.