We've also just started seeing this crash in our app in the last week... the app seems to crash within a few seconds of starting up and usually after being backgrounded/foregrounded. Both crashes were on iPhone X devices running 12.0.1 or 12.1. Haven't been able to reproduce and there isn't a lot of references to the UISnapshotWindow class but probably related to the device capturing a screen shot of the app state when going into the background (if I had to guess).
The crash is being captured by BuddyBuild crash reporting but not the AppStore crash reporting.
Application Specific Information:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_UISnapshotWindow actualSceneBounds]: unrecognized selector sent to instance 0x11650f380'
Last Exception Backtrace:
0 CoreFoundation 0x000000019fc27ef8 <redacted> + 228
1 libobjc.A.dylib 0x000000019edf5a40 objc_exception_throw + 56
2 CoreFoundation 0x000000019fb3f154 <redacted> + 0
3 UIKitCore 0x00000001cca865c0 <redacted> + 280
4 CoreFoundation 0x000000019fc2d810 <redacted> + 1412
5 CoreFoundation 0x000000019fc2f4bc _CF_forwarding_prep_0 + 92
6 UIKitCore 0x00000001cc857d2c <redacted> + 620
7 UIKitCore 0x00000001cc85a108 <redacted> + 5736
8 UIKitCore 0x00000001cc86662c <redacted> + 52
9 UIKitCore 0x00000001cc85df80 <redacted> + 656
10 UIKitCore 0x00000001cc8665ec <redacted> + 80
11 UIKitCore 0x00000001cc85d8fc <redacted> + 56
12 UIKitCore 0x00000001cc8d9548 <redacted> + 144
13 UIKitCore 0x00000001cc8f5030 <redacted> + 280
14 UIKitCore 0x00000001cc8d93f4 <redacted> + 140
15 UIKitCore 0x00000001cc8d9b0c <redacted> + 168
16 UIKitCore 0x00000001cc8e7b98 <redacted> + 552
17 CoreFoundation 0x000000019fb94d14 <redacted> + 20
18 CoreFoundation 0x000000019fb94ce0 <redacted> + 64
19 CoreFoundation 0x000000019fb941d0 <redacted> + 392
20 CoreFoundation 0x000000019fb93e7c <redacted> + 96
21 CoreFoundation 0x000000019fb0c1c0 <redacted> + 1404
22 CoreFoundation 0x000000019fb93908 _CFXNotificationPost + 696
23 Foundation 0x00000001a05a2eb0 <redacted> + 68
24 UIKitCore 0x00000001cca71904 <redacted> + 232
25 UIKitCore 0x00000001cc2f8684 <redacted> + 2180
26 UIKitCore 0x00000001cc2f6334 <redacted> + 772
27 UIKitCore 0x00000001cc2f5fe0 <redacted> + 432
28 UIKitCore 0x00000001cc2fb1a0 <redacted> + 220
29 UIKitCore 0x00000001cc2fc100 _performActionsWithDelayForTransitionContext + 112
30 UIKitCore 0x00000001cc2fb058 <redacted> + 248
31 UIKitCore 0x00000001cc2ffd9c <redacted> + 368
32 UIKitCore 0x00000001cc641118 <redacted> + 468
33 FrontBoardServices 0x00000001a26585a0 <redacted> + 228
34 libdispatch.dylib 0x000000019f660484 <redacted> + 16
35 libdispatch.dylib 0x000000019f6373f0 <redacted> + 216
36 FrontBoardServices 0x00000001a2696640 <redacted> + 40
37 FrontBoardServices 0x00000001a26962cc <redacted> + 416
38 FrontBoardServices 0x00000001a26968e8 <redacted> + 56
39 CoreFoundation 0x000000019fbb65b8 <redacted> + 24
40 CoreFoundation 0x000000019fbb6538 <redacted> + 88
41 CoreFoundation 0x000000019fbb5e1c <redacted> + 176
42 CoreFoundation 0x000000019fbb0ce8 <redacted> + 1040
43 CoreFoundation 0x000000019fbb05b8 CFRunLoopRunSpecific + 436
44 GraphicsServices 0x00000001a1e24584 GSEventRunModal + 100
45 UIKitCore 0x00000001cca58bc8 UIApplicationMain + 212
46 <OUR_APP> 0x000000010044e0f0 _mh_execute_header + 24816
47 libdyld.dylib 0x000000019f670b94 <redacted> + 4