Unable to convert stl file to FE mesh of a shell part

I am working on lattice structures. Recently I have imported .stl file in PrePoMax and the software could not able to identify the edges. I have used the feature “find edges by angle”, but it is identifying unnecessary edges and also I tried by entering a large angle but I encountered error. Which is creating problem when I am trying to generate mesh. I saw a video on LinkedIn in which they imported stl file of gyroid and the software identifies the edges accurately and in my case the software did not. I am unable to find the error. It will be really great if anyone can help me with this.

Can you share the file ?

maybe the model size is too small, try to scale the part by large number e.g 1000 then revert after successful.

I tried to increase the angle to find the edges of the model and it worked.
Thanks!