We have a project we are testing in Unity v5.6.0f3 which builds a large number of assetbundles. Up to this point, this project has been able to build assetbundles for individual assets efficiently and quickly using the (now obsolete) BuildPipeline.BuildAssetBundle() function. Now we are trying to use the 5.x version with BuildAssetBundles() however each time we do this, it forces a reimport of sorts: "Hold on: Determining assets that need to be reimported for target platform" "Hold on: Calcuating asset hashes" This happens even if only a single assetbundle is built. This would render the entire project useless because of the time it takes to perform these calcuations. Is this a bug? A single assetbundle shouldn't take over a minute to build. This happens whether we use the SetAssetbundleNameandVariant API *or* build the assetbundle(s) using a Build Map. FWIW we use the 5.x assetbundle system in a separate project in v5.3.7 w/o problems. I will save my gripe about losing the BuildAssetBundle() capability for another day Thanks for any assistance.