Can’t say I’m seeing this behaviour in the current ARV 7.1.4 or AR6.
There was a bug sampling in the early ARV release, now fixed, that was dependent on the size of canvas, small ones being the problem and if the sampling was from specific areas of the canvas, towards the bottom or right hand side. But as I say, now fixed.
Can you give any more info, like exact steps to reproduce or an example file where the colour sampling is consistently incorrect?
Also AR version and OS.
With the “alt” key sampling method, it is dependent on what settings have been applied in the ‘Colour Sampler’ tool’s Settings panel.
Make sure ‘With Lighting’ is turned Off, so it only picks the true colour.