Access Groups not working

Summary:

Added two access groups

Group 1:
Group Members: Employee A
Object Rule: Allows full access
Condition: Cases with Case Type = 'XXXXX'

Group 2
Group Members: Employee B
Object Rule: Allows full access
Condition: Cases with Case Type = 'YYYYY'

Employee B added a case with type 'YYYYY' that is accessible for Employee A - is there anything missing here to stop Employee A from seeing the case type 'YYYYY'

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