The issue is if you change something in XML schema via Manage Global Resources, it is not reflected immediately and it requires a restart of the gateway so that edit comes into effect.
Issue is reproducible in following scenario -
-Validate XML schema assertion targets a parent schema
-Child schema which is imported by parent schema is modified by user via Manage Global Resources
in policy manager.
This seems to be due to some cache policy and is occurring in a situation where the system has cached the parent schema but not child schema.
Now if child schema is changed after this state is reached, the cache will not be updated and when a lookup is done, the cached parent schema will be retrieved which has a stale version of child schema.
There is a workaround for this issue without gateway restart - After the required modification in child schema, if you open parent schema via Manage Global Resources and do some insignificant change (like add some extra space) and then save. Then you required child schema changes will also get reflected immediately.
Essentially the workaround is to open and edit the parent schema added in assertion so that their change to the child schema is picked up.