Steps to reproduce:
1) Open the attached project.
2) Build and run on an Android or iOS device (with .NET 4.6 and Mono enabled).
3) Wait for a couple minutes.

After 'Funds' (top-left corner of the screen) reaches a certain value, assert messages should start logging in ADB logcat console, however, when .NET 3.5 and Mono backend is used, NullReferenceExceptions are logged instead:
12-04 11:52:37.413 27405 27421 E Unity : NullReferenceException: Object reference not set to an instance of an object
12-04 11:52:37.413 27405 27421 E Unity : at (wrapper stelemref) object:stelemref (object,intptr,object)
12-04 11:52:37.413 27405 27421 E Unity : at UnityEngine.Assertions.AssertionMessageUtil.GetMessage (System.String failureMessage, System.String expected) [0x00012] in /Users/builduser/buildslave/unity/build/Runtime/Export/Assertions/Assert/AssertionMessageUtil.cs:20

On iOS, lldb-rpc-server crashes (log attached).
This does not occur with .NET 4.6 or IL2CPP.

Reproduced on:
2018.1.0a7, 2017.1.1f1

Note: this issue is related (and likely has the same roots) as case 974478.

===========

Resolution:

Given that this issue doesn't persist in new scripting runtime (.NET 4.x) or with IL2CPP, we are not planning on fixing this issue in the old Mono runtime.