My R2's IR sensor wouldn't probe my new flex plate Buildtak. I could hold the plate under the sensor and move it around and not get the monitor LED to come on. Putting other things under there worked fine. Paper, my hand, metal, whatever. So I got a small, flat aluminum plate about 4x6" and I lay it on the bed while it pre-heats so it equalizes temperature throughout and stays flat. As the 9 point probe routine runs I slide the plate around to keep it under the sensor, then pull it out before the printing starts. It's working great. The thickness of the plate doesn't matter because the probing is just comparing relative heights to check level. The actual printing offset is still taken from the Z-offset you put in, either from the Wizard or manually in the LCD Eprom setting dialog. I'm thinking of getting an 8.5 x 8.5" flat plate so I don't have to slide it around The 4x6 was the first one I had available nice and flat. I guess if I did ABS at 100C I'd want some light cotton gloves to protect my finger tips.... Or maybe make a plastic or wood handle for the plate. I was also getting some communication errors but I reseated all the connectors I could reach by removing the electronics cover near the bottom of the machine. Now it's like a new printer again Even after running the bed leveling wizards and adjusting the thumb screws and doing the auto-level, when I print a large, thin rectangle almost to the limits of the machine bed I see a tiny difference in smoosh of the first layer over near one corner, but it doesn't seem to be bothering my PETG prints. Measuring the resulting thin part I see about .1 mm thickness variation.