if you create a child containment entity off Global and further entity off this entity so you have
.....|__level 1 ent
................|_ level 2 ent
and create one date attribute in global (the global date) and another in level 2 ent (level 2 ent's test date). Also a boolean attribute in level 2 ent (the level 2 date test is passed) and then write a rule like
the level 2 date test is passed if
..................the global date is later than level 2 ent's test date
Now build this as a module and link to the module from a blank project and debug without screens in the 'host' project and all runs as it should.
Now if you change the rule to the level 2 date test is passed if
..................the global date is later than the date 60 days after level 2 ent's test date
and build, link and debug the module in the 'host' project you get the error "attribute 'level2enttestdate' does not exist in entity global in module 'module entity test'"
OPA seems to now be looking for the level 2 attribute at global level. I noticed this in a largish rulebase and have been able to replicate it in the stripped down version above.