Build failed — and no other messages... (!!?)

Having this issue with both the latest release version (2019.3.5) and EAP (2020.1 EAP). Build takes forever to start (it starts instantly in Xcode, and completes in under 0.79 seconds), and when it finally does start, takes a while (10 seconds in this case) before finally, and unhelpfully, informing me that "Build failed". No further error messages (at all). So, I have to switch to Xcode and build there... perhaps a not-so-subtle hint from the Jetbrains team that I should stick with Xcode :-) ?