Predicate String Frozen

bug MJSONWP Calling XCUITestDriver.findElements() with args: ["-ios predicate string","visible = 1","948c7ce9-7574-42f6-a600-0c7885f61029"]
dbug XCUITest Executing command 'findElements'
dbug BaseDriver Valid locator strategies for this request: xpath, id, name, class name, -ios predicate string, -ios class chain, accessibility id
dbug BaseDriver Waiting up to 5000 ms for condition
dbug JSONWP Proxy Matched '/elements' to command name 'findElements'
dbug JSONWP Proxy Proxying [POST /elements] to [POST http://localhost:8100/session/6155DF94-376C-4673-A8E6-6FA6FFC2E18B/elements] with body: {"using":"predicate string","value":"visible = 1"}
info Xcode     t =    67.43s Snapshot accessibility hierarchy for app with pid 93495
info Xcode 
info Xcode     t =    67.56s Snapshot accessibility hierarchy for app with pid 93495
info Xcode 
info Xcode 2018-09-11 13:47:22.327519-0700 WebDriverAgentRunner-Runner[93494:9770667] [general] Exception caught during decoding of received reply to message '_XCT_fetchAttributes:forElement:reply:', dropping incoming message and calling failure block.
info Xcode 
info Xcode Exception: Exception while decoding argument 0 (#1 of invocation):
info Xcode <NSInvocation: 0x600003381a40>
info Xcode return value: {v} void
info Xcode target: {@?} 0x0 (block)
info Xcode argument 1: {@} 0x0
info Xcode argument 2: {@} 0x0
info Xcode 
info Xcode Exception: value for key 'NS.objects' was of unexpected class 'XCAccessibilityElement'. Allowed classes are '{(
info Xcode     NSDictionary,
info Xcode     NSDate,
info Xcode     NSSet,
info Xcode     NSOrderedSet,
info Xcode     NSString,
info Xcode     NSNumber,
info Xcode     NSArray,
info Xcode     NSData,
info Xcode     NSNull
info Xcode )}'.
info Xcode