Displayed Gumball Bug?

This may be one of those I-don’t-THINK-it-looked-like-this-before issues…

Drag-selecting some curves and points, the gumball arrowsheads were black when the mouse was away from the focused View window
15%20AM

…hovering the mouse over the focused View window (Perspective in this case) the colors would come back to the gumball across all the other views.
49%20AM

In this same session, I have a second Rhino document opened – a Rhino 5 model. Switching over to it, the gumball has outright disappeared even though the gumball activation button at the top can be seen as toggled ON.
08%20AM

If I toggle gumball OFF then ON again (for this Thing 5 model), the gumball displayed across all four views has a blackened Z axis arrowhead and stem. X and Y are colored.

Haven’t yet had time to close it all out to replicate it yet.

Rhino 6 SR15 2019-4-9 (Public Build, 6.15.19099.12046, Git hash:master @ 00878fbc356e8a3ae40dbaf4d502416407a02c6e)
License type: Beta, build 2019-04-09
License details: Stand-Alone
Expires on: 2019-05-24

Apple Intel 64-bit macOS Version 10.14.4 (Build 18E226) (Physical RAM: 16Gb)
Mac Model Identifier: MacBookPro10,1
Machine name: Carter’s MacBook Pro
Language: en-US (MacOS default)

NVIDIA GeForce GT 650M OpenGL Engine (OpenGL ver:4.1 NVIDIA-12.0.23 355.11.10.50.10.103)

OpenGL Settings
	Safe mode: Off
	Use accelerated hardware modes: On
	Redraw scene when viewports are exposed: On
	
	Anti-alias mode: None
	Mip Map Filtering: Linear
	Anisotropic Filtering Mode: Height
	
	Vendor Name: NVIDIA Corporation
	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: 1 GB
	Graphics: NVIDIA GeForce GT 650M
	Displays: Color LCD (258dpi 2x)

Graphics processors
	Intel HD Graphics 4000 (1536 MB)
	NVIDIA GeForce GT 650M (1 GB)
		Color LCD (1680 x 1050)

USB devices
	Apple Inc.: Apple Internal Keyboard / Trackpad
	Apple Inc.: Bluetooth USB Host Controller
	Apple Inc.: FaceTime HD Camera (Built-in)

Bluetooth devices
	Broadcom: Microsoft Sculpt Touch Mouse SDP Server     , Microsoft Sculpt Touch Mouse     , Microsoft Sculpt Touch Mouse PnP Server     

Third party kernel extensions
	None

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

Rhino plugins
	/Applications/RhinoWIP.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoCycles.rhp	"RhinoCycles"	6.15.19099.12046
	/Applications/RhinoWIP.app/Contents/PlugIns/NamedSnapshots.rhp	"Snapshots"	6.15.19099.1002
	/Applications/RhinoWIP.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/GrasshopperPlugin.rhp	"Grasshopper"	6.15.19099.12046
	/Applications/RhinoWIP.app/Contents/PlugIns/PanelingTools.rhp	"PanelingTools"	6.15.19099.1002
	/Applications/RhinoWIP.app/Contents/PlugIns/AnimationTools.rhp	"AnimationTools"	6.15.19099.1002
	/Applications/RhinoWIP.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Commands.rhp	"Commands"	6.15.19099.12046
	/Applications/RhinoWIP.app/Contents/Frameworks/RhMaterialEditor.framework	"Renderer Development Kit"	6.15.19099.1002
	/Applications/RhinoWIP.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RDK_EtoUI.rhp	"RDK_EtoUI"	6.15.19099.12046
	/Applications/RhinoWIP.app/Contents/PlugIns/Displacement.rhp	"Displacement"	6.15.19099.1002
	/Applications/RhinoWIP.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoDLR_Python.rhp	"IronPython"	6.15.19099.12046
	/Applications/RhinoWIP.app/Contents/PlugIns/RhinoRender.rhp	"Rhino Render"	6.15.19099.1002