Not that you need it, when you use setArray you have to know the size somewhere anyway...

It used to never report the size, that was a problem for internal algos that generated arrays since you'd have to count them. EP
added the convention where $var = sizeof($var[]) for returned arrays. But since $var and $var[] are 2 different entities, it's only
true of places where $var[] is populated internally by a twxproxy command. It would be nice to have a sizeof() command tho.
This isn't really a bug. And it shouldn't be changed, it'll break scripts if you do. Some of us are used to $var and $var[] being
completely separate, and we use them as such. If you need $var to report sizeof($var[]) in your script then init it at the top and
just "add $var 1" along the way.
IMO, $var should not automatically report sizeof($var[]) for every single array. It would be useful tho to have a SizeOf or ArraySize
command for times where it's needed.