I think Simulink has a series of ways to determine the signal dimensions. Propagation takes higher priority than back propagation, or the priority is determined by settings in the block.
In your snapshot, the model has errors because workspace data has not been located yet. The model won't pass "model update" thus the compileddimension is invalid.
To get compileddimension, the model has to pass "model update".
To pass "model update", the data for the "From Workspace" blocks has to be located.
