After releasing Logic Pro X 10.4 a little over a month ago, Apple has just made version 10.4.1 available for download.
The new version features quite an extensive list of bug fixes and performance enhancements.
Quite a few cases where Logic Pro X would unexpectedly quit have been fixed, and there are over 20 fixes/enhancements for Smart Tempo and the File Tempo Editor.
On the plugin side, there are several fixes for the new Chromaverb, Space Designer, and older stuff including EXS24, ES1, and even Pitch Shifter.
You'll find some fixes for Flex too.
For the complete list, check out Apple's Logic Pro X 10.4.1 Release Notes.
As always, don't forget to back up Logic Pro X if you're in the middle of an important project/gig!
There's a good link at the top of the Release Notes page.