Rebar set handles not available everytime in plan

[daniel.compel]

Hello,

Can someone please tell me why do I sometimes have these handles to extend the rebar set and sometimes not? For instance, when im creating sets for slab in plan. Its been boggling my mind for a while and its really helpful to have them everytime. And yes, I am using maximum spacing setting for rebar set. Thank you for any help in advance!

Dan