The SuccessCount value of a command block (set to Repeat | Unconditional | Always Active")  doesn't seem to be properly updated when running a command like "/execute if entity @e[type=minecraft:armor_stand,distance=..5]". This leads to a wrong redstone output strength with a comparator.

I place two armorstands next to it and the SuccessCount value is always "1" and never changes.

If I change the command block from "Always Active" to "Needs redstone" and then update the SuccessCount value manually the comparator is outputting the right signal strength.

Edit #1: It doesn't really seem to matter what settings you put your command block on, the signal strength will not change.