Dabbling with logistics, I'm trying to read the number of construction & logistics robots in a robo-port, and if that number is less than 150 respectively, enable inserters to insert new robots. The way I'm trying to do this is straightforward: connect the roboport to the inserters, and set "construction robots" "<" "100" for the enable flag on the inserter. (equiv. for logistics robots).
However, even though there are already more than 100 such robots in the port (by inspecting it, or mouse-over display for the logistics network information), the inserter is still enabled (see green lights in the screenshot), and merrily continues to insert.
If I set the the condition to "robots" ">" "100" (i.e., "greater than") it's disabled , but that seems incorrect to me.

Am I misunderstanding something, or is this a genuine bug?
[latest experimental version 0.16.49 as of writing]