BLTouch driving me mad please help

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I am having a similar problem. BLTouch is not functioning correctly. It thinks one side of my bed is 5+ mm above the other side. After that first G29, it crashed straight into the bed on a first layer calibration.

I turned off G29 and got the calibration first layer to print perfectly with just the z-offset setting. I then just immediately hit reprint with zero changes and it is shooting spaghetti 2mm off the plate. What could cause 2 back to back prints to be different?

I am on an Ender 3 Pro with TH3D_UFW_U1.R2.B5 firmware installed. I modified the firmware according to BLTouch and Teaching Tech on YT.

UPDATE:
Ran Bed Visualizer on Octoprint and got this error:
TypeError: WebGLRenderingContext.uniformMatrix4fv: Argument 3 could not be converted to any of: Float32Array, sequence.