Follow up from original post, I kept adding shims all season on the old boots until it was clear the instep volume was just too much. A few weeks ago I went in for a pair of Hawx Ultra Pros and also...

yup shims were the move - went back to the shop shortly after all the feedback from the post and spoke to a different tech who agreed and replaced the heel lifts with shims. Issues fixed all around...

I have a pretty high range of motion (I dont remember the exact measurement he took but he commented it was high and not an issue). I think for me it is purely a volume problem.

Thanks for all the...

Hey all, quick question for those that are more knowledgeable.

I've always had a pretty low instep volume and struggle with locking my ankle down even with the ankle buckle cranked all the way...