I have posted my concerns about this as well and feel it still needs refinement. One issue is that FIA counts as enemies, this in theory is fine, the issue is that FIA can often get stuck in odd positions. A good example is the St. Pierre Coastal point. FIA can get stuck in the water or under the map and this prevents the point from being able to be built on.
"Enemy in the area" does work both ways, one tactic that the defenders use now is to often check build privilege as a sort of radar to know if someone is hiding or nearby. I really don't think this mechanic is all that much better than the previous solutions and both present their own issues.

1.3.0.25:

Same behaviour

6 live players vs 1 enemy = we can't build anything

I think this is really a problem of game design. If capture point is in an area where buildings are present, then good luck finding that needle in the haystack

I think it is made like that to prevent it being exploited to see enemies nearby with build camera. Like in T187340
If so, maybe the build mode could be remade into a sort of "depot" like armory, where you just take building "kits" of certain compositions and carry them manually to a build location of your choice, then place them and build them into the full composition.
Instead of the birde-eye camera view, I mean.
Would absolutely take more time building stuff though, but maybe it is a bit more realistic aswell. It can also likely be expanded on with different build kits and items for different compositions, like sandbags etc.

@byNautiic
Bird-eye view model is ok.
If enemies are in building zone, game should make them invisible in building mode. Then add proportional presence. Two problems solved.