If you are clicking a link in a Pushpage and it is not viewable and you get a page not found error.
First Check the Pushpage issue link/url itself to see if the URL is Public facing
Then check the link and see if it has something like long and has the word push in it
If so this more than likely means you copied the link from a pushpage issue. Sometimes copying the link directly from a pushpage and not the original source can create a link to go a page not found error. Find the original link/URL and update that in the pushpage issue.