iOS: library not found for -lplugin_chartboost

All of a sudden, I can’t build with Chartboost on iOS. I did a successful build two days ago, made a few adjustments to some graphics and went to build this morning and the build fails after 44 seconds, during the “Collecting plugins locally…” stage with this message:

ERROR: Builder failed: ld: library not found for -lplugin_chartboost
clang: error: linker command failed with exit code 1 (use -v to see invocation)
BUILD ERROR: There was a problem linking the app.

I started out building with version 3601 targeting iOS 13.5 and now two versions of Xcode later I’m running 3619 targeting iOS 14, all with the same results. I can still build just fine for Android with Chartboost, and when I remove Chartboost from build.settings, the app builds for iOS no problem.

I also tried removing the com.chartboost folder from ~/Solar2DPlugins/Caches/Solar2Directory/coronalabs/com.coronalabs to see if forcing a new download of the plugin would solve the problem. Solar downloaded a new copy of the Chartboost plugin from the server as expected, but the problem persisted.

Does anyone have any thoughts?