The PDF print happens as a background task and we do not give a progress bar for it as is the case for Interactive PDF. Maybe because the file you are exporting is large and are exporting a high quality one it may be taking time. You may be better able to judge the completion once you can see the progress.
For print PDF if you want to see the progress bar then you can:
1. Open the background tasks panel (Window > Utilities > Background tasks)
Yes a pretty useless indicator at the top of the control bar shows that a pdf is being written, it's not clickable to open the background task menu. And it's very obscure.
You must wait unitl the PDF has finished being created.