The local printing with the OS X client is not fully stable. See bug 2179. The code is not perfect either: Errors are silently dropped, and the code should probably be restructured.
One example of lacking error handling: > Strange. If I activated the support for the printer dialog in tlclient, the > printing works. Even stranger, after that it works nicely with the default > printer mode as well. Perhaps we just have bad error handling for when there is > no default printer.