  One of the features of many-body quantum systems with Hilbert-space
fragmentation is the existence of stationary states manifesting quantum
jamming. It was recently shown that these are "states with memory", in which,
e.g., measuring a localised observable has everlasting macroscopic effects. We
study such a measurement catastrophe with an example that stands out for its
clarity. We show in particular that at late times the expectation value of a
charge density becomes a nontrivial function of the ratio between distance and
time notwithstanding the corresponding current approaching zero.
