It might be worth asking Bluehost. I can't think of anything other than some sort of connectivity issue that would cause this. I think I saw that you had enabled Debugging and tried it. Did you check the web server's error log (or ask Bluehost if you don't have direct access). It's well worth putting a bit of effort into finding any warnings or notices that might provide a clue.
In the old days we had to install and upgrade plugins by changing them ourselves in the code area. I would expect that most will still have the appropriate instructions in the plugins database. If you are stuck you can always ask
This is one of the many reasons for showing restraint with adding optional plugins!
EDIT:
Just clutching at straws here... in your other post you spoke about a copy of a live site. If you have copied this site from somewhere else, is it possible your proxy settings in Moodle have been set? It's worth checking those settings anyway (Site administration > Server > HTTP).