I can't seem to dynamically set zlmaxsize greater than 256 using messages or the attribute inspector. Also, I can only decrease the value, never increase it. It works fine if I explicitly use @zlmaxsize in the object. Am I doing something wrong?
You can change it on the fly, but in your example what's happening is that zl.group on the left is initialized with a default zlmaxsize of 256, so the argument 1024 it too big for the actual size that zl.group is ready to receive so 1024 is replaced by the maximum size (256). When you change the zlmaxsize afterward, zl.group doesn't update the number of elements to group so it still stays at 256. You have to send the number of elements to group again after changing the zl.group size.