After apparently no critical show-stoppers were found during the beta phase, the new release of MMX version 14 is now officially available. MMX Setup
A list of changes can be found in the Change Log.
Besides the support for Delphi 10.3 Rio perhaps the biggest change is dropping support for oder Delphi versions. Since version 14 MMX will only support Delphi 10 Seattle and higher. For older versions you can still use version 13, which can be found at the MMX download page when clicking on Previous versions.
Dropping support for those older versions was inevitable to assure further development of MMX. It turned out that making things work for those Delphi versions would burn too much valuable time, which I can now dedicate to new features and the extension of existing ones.