Why did my chocolate tempering fail?
I'm going to blame your thermometers.
The one you used for your first batch you believe was a bad one, so it likely was measuring the temperature incorrectly, so you got poor results.
Then, you bought a really fancy infrared thermometer... which is great for measuring surface temperature but is pretty useless for anything else. Note that surface temp is usually much different than internal temp. Generally, if you're heating something up, the surface will be hotter than the inside and if you're cooling something down, the surface will be cooler than the inside.
This means that all your temperature readings were wrong!
Here's some info about the internal temperature reading myth:

2. An infrared thermometer will tell you the internal temperature
This is another myth worth busting. An infrared thermometer is a surface temperature tool – period. If you’re grilling, baking, smoking, or roasting you’re going to need a penetration probe to tell you the internal temperature of the food you’re cooking. An infrared will only give you the surface temperature of the food, and depending on your optical range, the temp of the surrounding grill, skillet, oven, etc.

I think you should try your chocolate tempering again but with a good-quality instant read thermometer (make sure the temperature range goes low enough) or a candy thermometer (again, some of them start at 100 F, so make sure it goes to the temps you need).