Why does my Simscape (mechanical translational) model fail to move when a force is applied?

I am modelling a mass-spring system which is excited by a sinusoidal force as below: 

However, the output from the "Ideal Translational Motion Sensor" shows that the components have 0 velocity in this setup. Why is this occurring, and how do I rectify this? 

Answer 1

[MathWorks Support Team]

The issue is because of the use of the "Ideal Force Sensor" block. In particular, the issue is occurring as it is connected in parallel between the spring and the Mechanical Translational Reference (ground). 

As described in the

Ideal Force Sensor

documentation, "the sensor constrains ports R and C to allow no motion between them, therefore connecting the sensor in parallel may affect the simulation results because it is analogous to adding a bypass connection line between the connection points."

The issue can be resolved by either commenting out the "Ideal Force Sensor" block or by connecting it between the spring and the mass so that it is now in series, as shown here: