That's weird because I had the same issue as you and using the @hbtarget is what fixed it for me.
Just out of curiosity, what button do you have this assigned to?
If you try the @hbtarget macro on another button, does it work as expected?
Does it only fail immediately after coming out of a form or anytime?
Are you trying to cast your macro on players who may be too low level to receive it? What if you cast it on a high level NPC, like a guard?
For me, the left button always reverts to Rejuvenation (Rank1) when I try to cast my macro, even in the betas and latest released build.