All child actor component parameters get "scrambled" after compiling a blueprint. How do I fix this?

[The_Compiler]

I recently migrated from 4.16.3 to 4.17.2 and a few days later I noticed something very odd.

I have a bunch of actors scattered across a level. These actors have child actors that have been given parameters to influence how they behave. Adding any sort of component to a separate blueprint and compiling it causes ALL the parameters of ALL the child actors of ALL actors to swap values with each other.

The result is that all actors still work, but their behaviour has changed to that of a different actor of the same type.

I can’t work with the project in this state. I’d VERY much appreciate any suggestions/workarounds.

[The_Compiler]

Apparently 4.17 comes with something called the “Compilation Manager”.

I went to Edit > Project Settings > Editor > Blueprints and then turned off Use Compilation Manager. Now my child actor parameters no longer get scrambled when I compile the character blueprint.