"-precompile" is used to precompile the engine into static libs (primarily for Rocket). According to BenM, recently modules have been made to opt-out rather than opt-in for this feature (because there were always missing modules in the Rocket build) and this broke this feature on Linux since some modules don't compile on it.
Appropriate build.cs need to be corrected to restore that.
See also [Link Removed]
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-25977 in the post.