Because of database performance optimizations added with this release, Collection Databases used in Engine DJ 4.1.0 are only compatible with version 4.0.1 or later.
If a drive, USB stick or SD card is used with 4.1.0, the collection will be updated in a way that will only be compatible with versions 4.0.1 or later.
Engine 4.1.0 is out: https://enginedj.com/downloads
The website says: