Paintbrush parts?

[JH4C]

Okay, massed minds, here's a clever one for you:

I'm in the SPH. Turn on Mirror Symmetry. Pick up a light from a mod or one from stock, and move the mouse over my craft to place it... And it turns into a paintbrush, smothering the surface of my craft with duplicate lights. ETA: I hadn't checked the VAB, but have now - same thing happens with the same parts, whether I select Radial symmetry or Mirror (anything other than solo part placement.)

I have a significantly modded install, but I know this didn't used to happen before 1.4.5/MH1.4. The only mods I use which affect placement of parts (AFAIK) are EditorExtensionsRedux and PartAngleDisplay, and removing either/both makes no difference. The painted parts can be picked up and destroyed like normal parts, but they don't count as part of the craft - they don't save with it, nor do they cause the parts count to increase. The log reports the following for every individual part painted, but no other error is recorded:

[EXC 16:30:43.505] ArgumentOutOfRangeException: Argument is out of range.
Parameter name: index
	System.Collections.Generic.List`1[PartModule].get_Item (Int32 index)
	PartModuleList.get_Item (Int32 index)
	Part.OnWasCopied (.Part newPart, Boolean asSymCounterpart)
	EditorLogic.createSymmetry (Int32 mode, .Attachment attach)
	EditorLogic.<SetupFSM>m__D ()
	KerbalFSM.UpdateFSM ()
	EditorLogic.Update ()

It doesn't happen for every light though; AviationLights appear to be entirely immune, as does the BahaSP target-following Spotlight and IndicatorLights' BL-01. The stock Round/Square lights, the round/square lights provided by Grounded, the beacon from AirplanePlus, and ChopShop's LED headlight all become paint brushes. SurfaceLights is the most confusing of all; the 4-way light cluster works fine, but the omni and surface spotlight become brushes. There appears to be no problem with the models on load, as there's no errors associated with any of them in the log - here's an example log using my Sandbox playthrough, but this is also occurring in Career: JH4Clightbrushes.zip. Oh, and here's a list of my addons - hyphens at the start of the line indicate that the line in question contains a child of the line above.

[x] Science!
000_AT_Utils
000_ClickThroughBlocker
001_ToolbarControl
AFLC
AirlockPlus
Airlocks
AirplanePlus
AllYAll
AnimatedAttachment
AntennaHelper
AntennaSleep
AquilaEnterprises
- ActionGroupManager
AviationLights
BahaSP
- Plugins
- - BDAnimationModules.dll
- - CritterCrawler.dll
- - RNModules.dll
BasicDeltaV
BasicOrbit
BetterBurnTime
BetterCrewAssignment
BetterTimeWarp
Chatterer
ChopShop
CommunityTraitIcons
CraftManager
CRE
CrewLight
DecouplerShroud
DockRotate
DodoLabs
DoubleTapBrakes
EarnYourStripes
EasyBoard
EasyVesselSwitch
EditorExtensionsRedux
EVAEnhancementsContinued
Firespitter
FlagRotate
FP_DPSoundFX
FShangarExtender
FuseboxContinued
GravityTurn
Grounded
ImprovedChaseCamera
IndicatorLights
IndicatorLightsCommunityExtensions
JanitorsCloset
JX2Antenna
KeepItStraight
KEI
KerbalEngineer
KerbalFoundries
KerbalGPS
KerbalJointReinforcement
KerBalloons
Kerbaltek
- Hyperedit
KerboKatz
KOOSE
KSPRescuePodFix
KSPWheel
KWRocketry
MandatoryRCS
MandatoryRCSPartPack
ManeuverNodeEvolved
MechJeb2
MiningExpansion
MissingHistory
MK1CabinHatch
Mk1PrototypeCockpit
Mk3HighGroundPlates
ModRocketSys
ModuleManager.3.0.7.dll
NameGenerator
NASA_CountDown
NavBallDockingAlignmentIndicatorCE
NavHud
NavyFish
- Plugins
- - Docking Port Alignment Indicator
- - ToolbarIcons
Notes
NRAP
OpenCockpit
PartAngleDisplay
PartOverhauls
PortraitStats
QuickMods
- QuickBrake
- QuickSearch
QuizTechAeroContinued
RCSBuildAid
ReCoupler
RecycledParts
RetractableLiftingSurface
RLA_Reborn
RocketEmporium
SensiblePumpsCont
ShipManifest
SmartActuation
SoundtrackEditor
SpaceTaxi
SpeedUnitAnnex
Squad
SquadExpansion
SquiggsySpaceResearch
SRCS
StageRecovery
SurfaceLights
SXT
TacSelfDestruct
TakeCommand
ThrottleControlledAvionics
TokamakIndustries
TooManyOrbits
TrackingStationEvolved
TriggerTech
VABReorienter
VectorRepurposed
VentralDrill
VesselMover
WaypointManager
WernherChecker
WetterWingsMM
WheelSounds
WhoAmI
WorldStabilizer

No other surface attachable item I tested appears to suffer this incredible glitch - and I tested SO many. Tell me, oh great sages - what in the name of Jeebus H. Kerman is going on?!

Edited August 24, 2018 by JH4C
Tested in the VAB to correct an oversight

[Gargamel]

I have no help for this, but I'd love to see some pics. 

[JH4C]

A picture's worth a thousand spotlights words... Also note, despite mirroring being set on the painting effect only occurs on the face you're actually moving your mouse over.

I'm slowly working through my mods, trying to pinpoint whichever's causing this, but it takes so long to reload...

[JH4C]

Found it - it's CrewLight. More specifically, because it's very specific, it's this one particular setting in the config file:

{
	use_motion_detector_light = True // enable the feature, lights must be set individualy, in flight or in the editor
}

The default for this setting is False. I'd set it to true because I never use it, and wanted to remove it from the part menus for simplicity... With hilarious consequences! *Studio applause*

How bizarre...