The following features are new in Mudbox 2020. For the list of what's fixed, see the Mudbox 2020 Release Notes.
Mudbox can now exchange model information directly with Autodesk Flame. Use to create a data link between Mudbox and Flame. Once created, this link supports an iterative, round-tripping workflow: start with a scene in Flame, export a geometry to Mudbox for added sculpting detail, and then merge it back to the original scene.
For details, see Import a model from Flame and Send files to Maya, 3ds Max, Softimage, and Flame.