I can confirm this is still happening in Beta 6. I'm not sure Apple will believe this is a problem unless they are testing with a Sticker Pack containing animated stickers (10 or so frames) and at least 10 or more stickers. If Apple wants people to actual buy sticker packs, static un-animated stickers or packs of very few stickers, just aren't going to attract buyers. This seems like a HUGE problem this late in the game.
I've tested on both Sierra and El Captitan. On Sierra the app just stalls Compiling, and on El Cap my apps usually crash with exit code 255...
*** First throw call stack:
(
0 CoreFoundation 0x00007fff888a14f2 __exceptionPreprocess + 178
1 libobjc.A.dylib 0x00007fff92bd2f7e objc_exception_throw + 48
2 CoreFoundation 0x00007fff888a1439 -[NSException raise] + 9
3 IDEInterfaceBuilderKit 0x0000000108ef784a -[IBAbstractPlatformToolProxy _errorByAddingAdditionalCrashInformationToError:orRaiseIfNeededOnFailure:shouldRaiseOnFailures:waitForCrashLog:] + 1579
4 IDEInterfaceBuilderKit 0x0000000108ef71f5 -[IBAbstractPlatformToolProxy errorByAddingAdditionalCrashInformationToError:orRaiseIfNeededOnFailure:] + 94
5 IDEInterfaceBuilderKit 0x0000000108ef881e -[IBAbstractPlatformToolProxy _ON_QUEUE_sendMessage:toChannelReturningError:during:] + 228
6 IDEInterfaceBuilderKit 0x0000000108ef8652 __74-[IBAbstractPlatformToolProxy sendMessage:toChannelReturningError:during:]_block_invoke + 38
7 libdispatch.dylib 0x00007fff970a240b _dispatch_client_callout + 8
8 libdispatch.dylib 0x00007fff970a39f2 _dispatch_barrier_sync_f_invoke + 74
9 DVTFoundation 0x00000001079e3c92 DVTDispatchSync + 206
10 IDEInterfaceBuilderKit 0x0000000108ef8575 -[IBAbstractPlatformToolProxy sendMessage:toChannelReturningError:during:] + 409
11 IDEInterfaceBuilderCocoaTouchIntegration 0x0000000113ee7f27 IBUISegmentConfiguration + 6970
12 IDEInterfaceBuilderCocoaTouchIntegration 0x0000000113ecf738 IBUIControlEventTypeToUIControlEventMask + 25078
13 IDEInterfaceBuilderKit 0x0000000108e5316c __84-[IBICAbstractPlatformAdapter compileSelectedItems:options:queue:completionHandler:]_block_invoke_2 + 286
14 DVTFoundation 0x00000001079e3d4c __DVTDispatchAsync_block_invoke + 156
15 libdispatch.dylib 0x00007fff970ad93d _dispatch_call_block_and_release + 12
16 libdispatch.dylib 0x00007fff970a240b _dispatch_client_callout + 8
17 libdispatch.dylib 0x00007fff970a703b _dispatch_queue_drain + 754
18 libdispatch.dylib 0x00007fff970ad707 _dispatch_queue_invoke + 549
19 libdispatch.dylib 0x00007fff970b572d _dispatch_main_queue_callback_4CF + 422
20 CoreFoundation 0x00007fff888569e9 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
21 CoreFoundation 0x00007fff888158dd __CFRunLoopRun + 1949
22 CoreFoundation 0x00007fff88814ed8 CFRunLoopRunSpecific + 296
23 IDEInterfaceBuilderKit 0x0000000108eb6563 -[NSRunLoop(IBIDEFoundationRunLoopAdditions) ib_spinRunLoopInMode:whileBlockExecutesConcurrently:] + 514
24 IDEInterfaceBuilderKit 0x0000000108eb6832 -[NSRunLoop(IBIDEFoundationRunLoopAdditions) ib_spinRunLoopInMode:waitingForSemaphore:] + 131
25 ibtoold 0x00000001076f2f66 ibtoold + 12134
26 ibtoold 0x00000001076f4824 ibtoold + 18468
27
Command /Applications/Xcode-beta.app/Contents/Developer/usr/bin/actool failed with exit code 255
Occasionally, with some packs I can get a build on either the Simulator, device or by archiving, but there doesn't seem to be a magic formula to making this happen. A lot of Clean Build Folder, restarting of Xcode, praying, etc.