As Istvan says, this has been reported by a number of users and is currently being investigated.
I have the same issue here running on a 2018 iPad Pro.
I find that closing and re-starting Shapr3D resolves the issue for a while, but after a while the tap issue returns.
I think Curiobot hit the nail on the head with his findings as described here:
Double-tapping issue with Apple Pencil - #5 by Curiobot