That’s because those models were created using a geometric modeling kernel that Shapr3D no longer uses—Open Cascade. Since 2017 (iOS app version 3.0), the app’s been running on Parasolid, a kernel that guarantees a reliable, stable, high-quality app experience and CAD compatibility.
If you’d still like to work on legacy models in the latest version of Shapr3D, please contact Shapr3D support via email and attach the models. The team will help you convert them into a Parasolid-compatible format.