Trying to understand hold time violation

There's something strange going on, but I can't tell from the diagram. You're right that the default hold requirement should be 0ns(launch at 0ns, latch at 0ns). My first guess is that you have a setup multicycle of 2 on this path. The default hold requirement is based on the setup requirement, so adding setup multicycles moves the default hold requirement. The way to fix this is to add a -hold multicycle of 1.