It seems that the code cannot sort out where the stress state is on the yeild surface.
You might have seen this already, but if not, there is a Camclay example input script documented in Section 4.11 of the R2023-R2 Material Reference Guide. That example will solve successfully with sample properties given for a 2D plane stress, (PLANE182) under a similar displacment load. Can you start with that example and substitute your material data in for comparison?
I assume that all your material inputs are in consistent N-Meter (Pa) units? You mentioned that aho=100kPa, but your INIST, appears to be in Pa. Not sure if that might be part of the issue.
You are navigating away from the AIS Discovery experience