Why does the explicit model concurrent execution partition ignores the 'TreatAsAtomicUnit' setting of a 'Function-Call subsystem' and requires it to be set as atomic again?

I'm using the "Enable explicit model partitioning for concurrent behavior" option for a model configured for current execution with both non-virtual blocks (to be attached to a Periodic Trigger) and Function-Call subsystems (to be attached to an Aperiodic Trigger). However, when updating the block, the Diagnostic Viewer prompts me that "This model is configured for concurrent execution and has modeling constraints. Block 'MATLAB_Answers_Model/Aperiodic_Interrupt' of type 'function call subsystem' must be contained in a referenced model or atomic subsystem.", despite the fact that this aforementioned block is already an atomic subsystem. How to workaround this problem?

Reproduction Steps:

• Download and open the attachment file MATLAB_Answers_Model.slx, note that the model contains both periodic atomic subsystem and atomic aperiodic Function-Call subsystem:
• Verify that the "Aperiodic_Interrupt" Function-Call Subsystem is already atomic by typing the following command in the MATLAB command window. Notice that MATLAB replies 'on' to this command:

get_param('MATLAB_Answers_Model/Periodic_Trigger', 'TreatAsAtomicUnit')

• Press Ctrl+E to open the Configuration Parameters, go to Solver tab, and click "Configure Tasks..." to configure the model for concurrent execution:
• Notice that the model has both Periodic Trigger and Aperiodic Trigger that corresponds to the Simulink model above. Click "Refresh mapping table" button as shown in the screenshot:
• See the error message: