Bug with the extend surface command

Hi there. Currently using Rhino for Mac 6 and there appears to be a bug in it with the extend surface command on already trimmed surfaces that is driving me batshit crazy.
This is on regular shaped surfaces with a continuous edge that is trying to be extended. Most time I try and extend a surface, the thing goes the other way and shortens the surface. I’m currently working on an Alloy Boat design that is requiring a lot of modification. 5 minute job (not really) in Rhino 5 OSX as all I’m doing is re trimming or extending existing surfaces in an existing design. With this Bug I’m having to literally take a border of the existing surface, Untrim the surface, redraw the border and then re-trim the surface to the new outline. This is on regular rectangular surfaces with the edge desired to be trimmed, being a continuous edge along its length.
The same model & same surfaces in Rhino 6 for PC is not appearing to do the same

Can you post a sample surface?

sample surface.3dm (311.6 KB)
Hi
See attached. This same surface when I try and extend the left end, in Rhino 6 for PC, extends the input distance, in the case of this particular surface I was trying to extend it 30mm. Menu - Extend Surface (or selecting from surface tools) - pick surface end - input 30mm - success
Same surface in Rhino OSX, using same method, the surface shortens by 30mm. Will not lengthen the surface >50% of the time I try and use the command.

Point of note, I am modifying an existing design, I cannot definitely say how the surfaces were created.

Hello - please try UntrimAll on the surface and see how it works after that (I do not have access to a mac at the moment, but I’ll test this)
Also please post the service release of the Mac version you’re using (SystemInfo command)

-Pascal

Hi. Been there, done that. Whole point of the issue the bug is creating is I am trying to avoid doing that in order to work with some relative efficiency and Rhino 5 OSX and Rhino 6.0 PC is allowing me to do so. The bug, if it is one seems limited to Rhino 6 OSX.

System Info
Rhino 6 SR17 2019-8-24 (Public Build, 6.17.19236.01022, Git hash:master @ 06b69c5cc21d880aa793a5a7cfd454a66f6213bb)
License type: Evaluation, build 2019-08-24
License details: Stand-Alone
Expires on: 2019-10-26

Apple Intel 64-bit macOS Version 10.14.6 (Build 18G95) (Physical RAM: 16Gb)
Mac Model Identifier: Macmini7,1
Machine name: Simon’s Mac mini (2)
Language: en-AU (MacOS default)

Intel Iris OpenGL Engine (OpenGL ver:4.1 INTEL-12.10.12)

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On

Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: Height

Vendor Name: Intel Inc.
Render version: 4.1
Shading Language: 4.10
Maximum Texture size: 16384 x 16384
Z-Buffer depth: 24 bits
Maximum Viewport size: 16384 x 16384
Total Video Memory: 1536 MB
Graphics: Intel Iris
Displays: PHL 273V5 (82dpi 1x)

Graphics processors
Intel Iris (1536 MB)
PHL 273V5 (1920 x 1080 @ 60 Hz)

USB devices
GenesysLogic: USB3.0 Hub
Seagate: FreeAgent GoFlex
Logitech Inc : Logitech USB Headset H540
PixArt: Microsoft USB Optical Mouse
Apple, Inc.: IR Receiver
Apple Inc.: Bluetooth USB Host Controller
Logitech: USB Receiver

Bluetooth devices
Apple: Apple Wireless Keyboard

Third party kernel extensions
com.kaspersky.kext.klsat (1.0.1a2) 58F200A6-265B-3863-89D2-D657BA34AF2C
com.kaspersky.kext.kimul (46) A8797394-1582-3199-B848-57168A700E56
com.kaspersky.kext.klif (3.6.12a2) 6BA1AFA7-F84D-3C69-9E56-0C3E21139D2E
com.kairos.driver.DuetDisplay (1) EBD32AC4-5147-35AE-9FA3-8B8BB38E4FBA
com.kaspersky.nke (2.4.0a6) 45D3BCC3-2FB1-37A1-8148-801CBB1D353B
com.google.drivefs.filesystems.dfsfuse (33.0.16) 478AED06-D747-34F7-8930-927A0553849C
com.devguru.driver.SamsungMTP (1.4.31) A7E0B5D7-7F18-FF68-E78D-8B807B44F6CF

Third party plugins
/usr/lib/log/liblog_network.dylib

Rhino plugins
/Applications/Rhinoceros 6.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoCycles.rhp “RhinoCycles” 6.17.19236.1022
/Applications/Rhinoceros 6.app/Contents/PlugIns/NamedSnapshots.rhp “Snapshots” 6.17.19236.1002
/Applications/Rhinoceros 6.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/GrasshopperPlugin.rhp “Grasshopper” 6.17.19236.1022
/Applications/Rhinoceros 6.app/Contents/PlugIns/PanelingTools.rhp “PanelingTools” 6.17.19236.1002
/Applications/Rhinoceros 6.app/Contents/PlugIns/AnimationTools.rhp “AnimationTools” 6.17.19236.1002
/Applications/Rhinoceros 6.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Commands.rhp “Commands” 6.17.19236.1022
/Applications/Rhinoceros 6.app/Contents/PlugIns/SolidTools.rhp “SolidTools” 6.17.19236.1002
/Applications/Rhinoceros 6.app/Contents/Frameworks/RhMaterialEditor.framework “Renderer Development Kit” 6.17.19236.1002
/Applications/Rhinoceros 6.app/Contents/PlugIns/import_ACAD.rhp “AutoCAD file import: import_ACAD” 6.17.19236.1002
/Applications/Rhinoceros 6.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RDK_EtoUI.rhp “RDK_EtoUI” 6.17.19236.1022
/Applications/Rhinoceros 6.app/Contents/PlugIns/Displacement.rhp “Displacement” 6.17.19236.1002
/Applications/Rhinoceros 6.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoDLR_Python.rhp “IronPython” 6.17.19236.1022
/Applications/Rhinoceros 6.app/Contents/PlugIns/RhinoRender.rhp “Rhino Render” 6.17.19236.1002