Crash when using UI Dropdowns

I haven't been able to create a minimal example of this crash, as it appears to occur based on something that happens with the database backend being used (and creating a minimal project with that backend would violate confidentiality), but here's what I do know:

- 5.5.2 evertything's fine
- 5.6.1 it crashes
- Crashes in the emulator and on the device
- When it crashes, the dropdown items stop rendering properly (that is, immediately on opening the dropdown the items are displayed, but as soon as the gaze point shifts, even a pixel, it crashes)
- Does not happen when the items are supplied to the dropdown via the Unity Editor Inspector
- Does not happen when adding items to the menu via hard-code, i.e. Start() { List<string> lst = ...; dropdown.AddOptions(lst); } (this is exactly how it is being handled with the values-from-the-database)
- Currently selected item in the dropdown (blacked out, below) continues to render fine, even as it's selection item stops rendering
- Crash occurs in pure Unity Engine code, no user code is referenced in the stack trace

 

Here's the full call stack.
I tried to get a crash dump as well, but it didn't generate; I'll keep trying.

Code (csharp):

1. >    UnityPlayer.dll!EvaluateObjectDepth(struct RenderLoopContext const &,class AABB const &,float,float &,float &)    Unknown
2.     UnityPlayer.dll!BuildRenderObjectData()    Unknown
3.     UnityPlayer.dll!DoRenderLoop(struct RenderLoop &,enum RenderingPath,struct CullResults &,struct ShadowMapCache &,bool)    Unknown
4.     UnityPlayer.dll!Camera::DefaultPerformRenderFunction::eek:perator()(class Camera *,enum RenderingPath,struct CullResults *)    Unknown
5.     UnityPlayer.dll!Camera::MultiCustomRender(struct CullResults &,class Camera::performRenderFunction * const *,unsigned int,bool)    Unknown
6.     UnityPlayer.dll!Camera::DoRender(struct CullResults &,struct SharedRendererScene const &,enum Camera::RenderFlag,class Camera::performRenderFunction *)    Unknown
7.     UnityPlayer.dll!Camera::CustomRender(struct CullResults &,struct ShaderPassContext &,struct CameraRenderingParams const *,enum Camera::RenderFlag,class Camera::performRenderFunction *)    Unknown
8.     UnityPlayer.dll!Camera::Render(struct CullResults &,struct ShaderPassContext &,struct CameraRenderingParams const *,enum Camera::RenderFlag)    Unknown
9.     UnityPlayer.dll!Camera::DefaultPerformEyeRenderFunction::eek:perator()(class Camera *,struct CullResults *,enum Camera::RenderFlag)    Unknown
10.     UnityPlayer.dll!Camera::RenderStereo(enum Camera::RenderFlag,enum CullFlag,class Camera::performEyeRenderFunction *)    Unknown
11.     UnityPlayer.dll!DoRenderScreenCamera()    Unknown
12.     UnityPlayer.dll!RenderManager::RenderCameras(int,void (*)(void))    Unknown
13.     UnityPlayer.dll!PlayerRender(bool)    Unknown
14.     UnityPlayer.dll!`InitPlayerLoopCallbacks'::`2'::postLateUpdateFinishFrameRenderingstruct::Forward()    Unknown
15.     UnityPlayer.dll!PlayerLoop(void)    Unknown
16.     UnityPlayer.dll!metro::MainLoop(bool)    Unknown
17.     UnityPlayer.dll!UnityPlayer::AppCallbacks::DoPerformUpdateAndRender(void)    Unknown
18.     UnityPlayer.dll!UnityPlayer::AppCallbacks::performUpdateAndRender(void)    Unknown
19.     UnityPlayer.dll!UnityPlayer::AppCallbacks::_AppThreadImplementation(void *)    Unknown
20.     UnityPlayer.dll!UnityPlayer::AppCallbacks::_AppThread(void *)    Unknown
21.     UnityPlayer.dll!<lambda>(void)()    Unknown
22.     UnityPlayer.dll!Platform::Details::__abi_FunctorCapture<class <lambda_3e1924211b9579f8e542f5342662ee9c>,void,struct Windows::Foundation::IAsyncAction ^>::Invoke(struct Windows::Foundation::IAsyncAction ^)    Unknown
23.     UnityPlayer.dll!Windows::System::Threading::WorkItemHandler::Invoke(struct Windows::Foundation::IAsyncAction ^)    Unknown
24.     UnityPlayer.dll!Windows::System::Threading::WorkItemHandler::[Windows::System::Threading::WorkItemHandler::__abi_IDelegate]::__abi_Windows_System_Threading_WorkItemHandler___abi_IDelegate____abi_Invoke(struct Windows::Foundation::IAsyncAction ^)    Unknown
25.     threadpoolwinrt.dll!6d264c6f()    Unknown
26.     [Frames below may be incorrect and/or missing, no symbols loaded for threadpoolwinrt.dll]  
27.     [External Code]