Sorry for the trouble this is causing! Would it be possible to send a copy of the document to our
support ninjas? (The "Send Feedback" item under the Help menu will even convert all text in the document to gibberish, if it contains sensitive information.)
I was able to generate lines similar to what you're describing - the Shift key
should be restricting straight lines to multiples of 45 degrees. I'm guessing that just means that the document that I whipped together isn't encountering the same thing you're seeing for some reason. If we have a copy of your document to work with, we should be able to get to the bottom of this fairly quickly. Thanks for the help!