Perhaps the following warnings from the diagnostic viewer may be helpful. They imply potential memory limitations even though my total memory usage hasn't hit 100%.
AVR Memory Usage ---------------- Device: atmega328p Program: 26272 bytes (80.2% Full) (.text + .data + .bootloader) Data: 1729 bytes (84.4% Full) (.data + .bss + .noinit)
Component: Simulink | Category: Block warning
Parameter InitialOutput cannot be downloaded because its type (CAN_MESSAGE_BUS) has no external mode host-to-target function registered
Component: Simulink | Category: Model warning
Saving external mode simulation output as a single object is not supported because the workspace variable 'out' is not created during model code execution. To suppress the warning, set 'ReturnWorkspaceOutputs' to 'off'.
Component: Simulink | Category: Model warning
Not enough memory on the target to process the packet: EXT_SETPARAM
Component: Simulink | Category: Model warning
Not enough memory on the target to process the packet: EXT_SELECT_SIGNALS
Component: Simulink | Category: Model warning