Zero stiffness in an active degree of freedom

A teaching single-DOF model has $P=50\text{ kN}$ and $K_x=0$.

Why an artificial tiny spring is not a valid stability fix

A $10\text{ kN}$ vertical load is placed on a mechanism direction. Someone adds a fictitious $0.001\text{ kN/m}$ spring only to make the matrix nonsingular.

Multiple analytical structures

A roof model is reported as more than one disconnected analytical structure.

A warning disappears after a change — is the model fixed?

A stability warning disappears after changing a member release.

Build a reviewable structural report

A high-rise or industrial model produces hundreds of pages of raw output. What belongs in the calculation package?