This morning the Canvas preview on the app I am developing starting displaying "Cannot preview in this file...". The diagnostics display complains:
MessageSendFailure: Message send failure for send previewInstances message to agent
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| RemoteHumanReadableError
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| LoadingError: failed to load library at path "/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib": Optional(dlopen(/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib, 0x0002): tried: '/Users/mark/Library/Developer/Xcode/DerivedData/BoxDesigner-gbhzycedtosmdoetkpwtcpuwawhb/Build/Intermediates.noindex/Previews/BoxDesigner/Products/Debug/MainView.1.preview-thunk.dylib' (no such file), '/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib' (code signature in <D4EED909-712E-3055-B429-BBA7EB77A196> '/Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib' not valid for use in process: mapped file has no Team ID and is not a platform binary (signed with custom identity or adhoc?)))
The file /Users/mark/Library/Containers/com.microenh.BoxDesigner/Data/MainView.1.preview-thunk.dylib is present.
I tried deleting the /Users/mark/Library/Containers/com.microenh.BoxDesigner folder and rebuilding. No change.