I'm running 2014a and I am using a Simulink model in External run mode. I have a few constant blocks I'd like to change the value of however they aren't all tunable during run time. For instance, Constant1 and Constant2 are connected to a Subsystem and Constant1's block properties are greyed out during runtime however Constant2's block properties I can change during runtime. They are virtually identically blocks wrt properties. Not sure what's going on here.