Version 3.57.0 (726)
Crash while shelling object.
tessellating bodies will take a really LONG time.
Crashlog
Shapr3D[6165].crashlog.zip (45.2 KB)
This is a different crash. It happens every time I try and open a particular drawing so I can’t export it and send it to you.
shpr_2021012400.crashlog.zip (42.5 KB)
Import this STEP ~50K triangle file. It finished on Mac and I could interact with it. When I close the app and come back in and try and open it the app crashes. the iPad crashes I think just before it presents the final drawing.
WideMouthLid.stp.zip (7.8 MB)
I am going to try and generate the same drawing but with ~20K triangles and see how that goes.
This issue usually comes down to running out of memory. When you load a WS Shapr tesselates everything, which creates this problem. When you create bodies in the WS, it happens little by little, so it is possible to create a WS which you can work in, but cannot open anymore. 
It is something our rendering team is working on to fix, but it’s not a quick or easy one.
This also means there is a good chance not to be able to open big WS created on Mac on iPad, since iPad has more limited available memory.
Also, please update to 3.57.1, it might help. 
Hi @Yepher, shelling a body is much more complex than it looks if you have something that detailed. Please try to imagine that when shelling, you are asking Shapr3D to do a surface offset from the outer surface to the direction you have selected while maintaining a closed body.
Offsetting the inner direction those tiny mounting point details (i guess?) with fillets around them can easily end up in an invalid body if the offset details intersect with each other.
Please try to get the simpler revolved shape and apply Shell on it, or project the body to a plane, offset the undetailed curves to revolve them and subtract the body to get a hollowed result