The shocks attachment point breaks after working with it. It only happens if the shock has been modified with xml or sometimes just with the property panel.
WORKAROUND:
Isolate the suspension, clone the part and connect it to the first part to test if the points are fixed. Repeat it and connect to the recent part if it doesnt work.
Old text:
It happens to a cloned part and after editing propertiess a couple of times, This was always a problemm since i started playing sr2. Im using the old version but im pretty sure its present on every update
It also happened to me, but not always.