New:
- GPU and Optimized viewport hair display modes now work under DirectX 11, they were only available with OpenGL before
- Refresh button for the graft groom list, and the list is rebuilt automatically when the contents of the grooms directory change
- Guide isolation in Edit Guides now nests: isolating within an isolated set and toggling again returns to the previous set, and guides planted while isolating stay visible
- Multiplier: new Recompute Surface Positions option, so copies moved by Spread or Shift get their own surface position instead of keeping the one of their source strand
- Groom operator: graft surface subdivision level
- The Remember Roots data of Guides From Mesh and Hair From Guides is now stored in the operator parameters, so it survives Save Groom and Load Groom
- Groom files now store the hard edges of the distribution mesh
- Alembic import loads unprefixed float and vector geometry parameters as strand channels, so channels exported through a layout and baked material colors survive a round trip
- Expressions in Generate Strand Data are evaluated by a built-in expression engine which replaces the SeExpr library. Noise-based expressions produce a different pattern than before
- Arnold and V-Ray procedural rendering writes the groom next to the exported .ass or .vrscene file instead of the temporary folder when no groom file name is set
- Even root generation and the Filter operator are faster through an optimized sample elimination

Fixed:
- Angle parameters were multiplied by 57.3 when a scene saved by version 5.1.8 or later was opened in a newer version
- Operator nodes randomly passed their input through after a scene load, changing combed guides and Detail point counts
- Hair From Guides took 30 seconds per evaluation with a shading network as the distribution map, and regenerated its roots on every interpolation edit while a map was connected
- Opening a scene with an Edit Guides node flagged the scene as modified
- Cut brush with the Line shape skipped strands whose crossing segment was longer than the brush size
- Clump stem shapes followed the auto-wired guides port instead of the guides that generated the hair, so smoothing above the Clump had no effect
- Hair object was not selectable in the viewport while an Edit Guides in its stack had an edit mode left on
- Edit Guides control points were only pickable where they were when first picked, and not at all under DirectX 11
- Clump node had no distributionMap attribute, which made the attribute editor error when the operator was added
- Save Groom lost the Hair From Guides interpolation settings, so the hair differed after Load Groom
- Moov Physics evaluation was aborted when the stored capture path pointed at an unreachable drive
- Edit Guides Surface tracking: combing a guide made guides planted after the edits jump, revert to their base length and change strand group
- "Invalid strand index -1" warning after deleting a guide and planting a new one in Edit Guides
- Edit Sinks tool crashed Maya when the selection changed while its manipulator was being set up
- Archive Scene did not include the Ornatrix external cache files
- Some Maya hotkeys could not be used while a brush was active, Ctrl and Alt chords and text field typing are now passed on to Maya
- Viewport dropped to a few frames per second after a slider change in GPU hair display mode, and degraded after repeated Show/End Result toggles with hidden guides
- Graft Groom tool killed Maya on undoing a fit, and when activated with a grafted hair shape selected
- Graft grooms sharing a file name were listed and loaded as the first one
- Graft groom fit scale is now measured on the graft surface area instead of the fit handle chord, so a groom recorded on one head fits others at the right size
- Graft surface vertex edits were ignored by the Wrap and Nearest fit methods with Soft Selection Iterations at 0
- Friction and restitution coefficient changes were ignored by Moov Physics until the simulation was reset