Long story short, try a smaller X-axis value for the detection volume size.
Watch the rest of that section in the video and ask yourself what the Detection Volume Size property and its XYZ properties are doing?
They are defining a volume used for detecting components. The volume is made using a tool frame and its coordinate system.
So if something below the parts is being picked… the Z-axis or height of the volume is too big. If something to the side of the parts like the batcher block on the conveyor… the X and/or Y-axis of the volume is too wide or long.
On the Academy, it shows that the tutorial was made using 4.0.0… wowzah!
My guess is the X-axis/length of the detection volume size is too big, so it is detecting the batcher block. I believe this might apply to both old and new versions of that conveyor.
At least the new one has a higher block, so try an X-axis value of 150 as shown in the video or switch the components. For example, I got the final layout from the lesson files in the Academy, and then switched out the old 4.0.0 version components with 4.1.1 and then made a new robot program using signals 100 onward.
If you want, attach your layout and I can quickly spot the issue.
4.1.1-Grasp-and-Release-Multiple-Objects-Final.vcmx (240 KB)