diff --git a/packages/kbn-optimizer/src/worker/run_compilers.ts b/packages/kbn-optimizer/src/worker/run_compilers.ts
index c7be943d65a48..d78eb8214f607 100644
--- a/packages/kbn-optimizer/src/worker/run_compilers.ts
+++ b/packages/kbn-optimizer/src/worker/run_compilers.ts
@@ -110,7 +110,7 @@ const observeCompiler = (
 
       const bundleRefExportIds: string[] = [];
       const referencedFiles = new Set<string>();
-      let normalModuleCount = 0;
+      let moduleCount = 0;
       let workUnits = stats.compilation.fileDependencies.size;
 
       if (bundle.manifestPath) {
@@ -119,7 +119,7 @@ const observeCompiler = (
 
       for (const module of stats.compilation.modules) {
         if (isNormalModule(module)) {
-          normalModuleCount += 1;
+          moduleCount += 1;
           const path = getModulePath(module);
           const parsedPath = parseFilePath(path);
 
@@ -154,7 +154,12 @@ const observeCompiler = (
           continue;
         }
 
-        if (isExternalModule(module) || isIgnoredModule(module) || isConcatenatedModule(module)) {
+        if (isConcatenatedModule(module)) {
+          moduleCount += module.modules.length;
+          continue;
+        }
+
+        if (isExternalModule(module) || isIgnoredModule(module)) {
           continue;
         }
 
@@ -180,13 +185,13 @@ const observeCompiler = (
         bundleRefExportIds,
         optimizerCacheKey: workerConfig.optimizerCacheKey,
         cacheKey: bundle.createCacheKey(files, mtimes),
-        moduleCount: normalModuleCount,
+        moduleCount,
         workUnits,
         files,
       });
 
       return compilerMsgs.compilerSuccess({
-        moduleCount: normalModuleCount,
+        moduleCount,
       });
     })
   );
diff --git a/packages/kbn-optimizer/src/worker/webpack_helpers.ts b/packages/kbn-optimizer/src/worker/webpack_helpers.ts
index e30920b960144..a1f97c4314774 100644
--- a/packages/kbn-optimizer/src/worker/webpack_helpers.ts
+++ b/packages/kbn-optimizer/src/worker/webpack_helpers.ts
@@ -155,6 +155,7 @@ export interface WebpackConcatenatedModule {
   id: number;
   dependencies: Dependency[];
   usedExports: string[];
+  modules: unknown[];
 }
 
 export function isConcatenatedModule(module: any): module is WebpackConcatenatedModule {
diff --git a/src/dev/build/build_distributables.ts b/src/dev/build/build_distributables.ts
index bfcc98d6cd9a8..1d41f4c270caa 100644
--- a/src/dev/build/build_distributables.ts
+++ b/src/dev/build/build_distributables.ts
@@ -63,17 +63,17 @@ export async function buildDistributables(log: ToolingLog, options: BuildOptions
   await run(Tasks.CopyBinScripts);
   await run(Tasks.CreateEmptyDirsAndFiles);
   await run(Tasks.CreateReadme);
-  await run(Tasks.TranspileBabel);
   await run(Tasks.BuildPackages);
   await run(Tasks.CreatePackageJson);
   await run(Tasks.InstallDependencies);
+  await run(Tasks.BuildKibanaPlatformPlugins);
+  await run(Tasks.TranspileBabel);
   await run(Tasks.RemoveWorkspaces);
   await run(Tasks.CleanPackages);
   await run(Tasks.CreateNoticeFile);
   await run(Tasks.UpdateLicenseFile);
   await run(Tasks.RemovePackageJsonDeps);
   await run(Tasks.TranspileScss);
-  await run(Tasks.BuildKibanaPlatformPlugins);
   await run(Tasks.OptimizeBuild);
   await run(Tasks.CleanTypescript);
   await run(Tasks.CleanExtraFilesFromModules);