When you beam the target often they can just hide behind the smallest geometry.
If it breaks line of sight it does not damage, even if inside its range.
I uploaded two screenshots, first with the expected outcome, second where Abrams is standing inside the beam range but just within a line of...
It does show up in the UI. To confirm I buy spirit burn and lvl 2 singularity. The range there is 9.9 meters. Buying knockdown then does not influence the range, it stays close to the 10m mark. Build #5826