KSP 1.11.0 broke a lot of old add'ons
OPT Legacy also broke due this problem.
Not tested it myself, but this was reported here:
Warning. WorldStabilizer no longer suppresses the 1km spawn bug as of KSP 1.11, and seems to actually evolve it into a new and vicious kraken.
Take extreme care when spawning crafts containing the following parts, or just don't use them anymore:
- Deployment Bay
- Inline Large Docking Port
- Avatar Cargo Ramp
- Humpback Cargo Ramp
- Stail Cargo Bay (Mk1, not Mk2)