Are you logging your package errors? Sounds like you need to do that to track down the error.
If the XLSM file is open and the other program then you know it makes it to <the whatever you ended up using to go to the PDF> . You said you did this a few ways so it's hard to say but that's one of the ways things can behave when waiting for user interaction or an answer to some prompt. Just one of a ton of possibilities. 

Sue