One possibility is that you're subconsciously engaging the right tib anterior MORE. I'm not accusing you of being a unilateral movement hater but I read about all these guys who swear they are balanced and unilaterals are for sissys. Smart money says most of these knuckleheads are not as balanced as they think they are.
You can try performing SMR and stretching on the right side. If you visit your local bike or running store, they should have what looks like plastic rollers on a short broomstick. This is one way to work on the adhesions there.
And also strengthen the left tib anterior so you build a more efficient neural connection. Until this is taken care of, I'd stay away from the GHR. If you are able to modify it so that you can use your arms for the concentric, it will be a good way to phase the movement back in.
And how much plantarflexion do you perform? If your tib anterior ( a dorsiflexor) is overactive, another piece to this puzzle is to strengthen the soleus and gastrocs. In other words, be that rare guy at the gym who actually does calf raises.