We recently fixed a compatibility issue with the latest Lightroom version.
Please download the updated version of our Lightroom plugin by going to our download section. The URL was sent to you in the welcome email you received after purchasing JPEGmini.
Once you've downloaded the new version, please follow these simple directions:
1) Close Lightroom
2) Uninstall and delete the current Lightroom plugin from the plugin manager
3) Reopen Lightroom
4) Replace the previous version with the updated version you just downloaded
5) Install the Lightroom plugin