As per title. Have run into this multiple times using manual airlocks to control flow of fluid between reservoirs. Upon load, manual airlocks set to closed will have fluid leaking through them, and their state will be listed as "auto". Resetting the state to closed corrects the problem.
I've been trying to use these airlocks to separate areas containing waste and clean water, but by the time I've reset the state upon load, a bunch of waste usually leaks into my clean reservoir.
1) Place Manual airlock. 2) Set airlock to closed. 3) Save and reload game. 4) Note airlock now set to auto.