Hi jleblancmango,
Hmm. I wonder,
What is store.url set to in your Mango/overrides/properties/env.properties or Mango/classes/env.properties files?
On the /ui/administration/modules page, what is your upgrade release channel, and what is your current version?
Is there anything in the log file going on?
This can occur if you're on the development channel and the latest were a development release: in that situation it will offer to update the development version endlessly (because we don't put out development modules or cores often, but if we do we'd be updating them frequently, as opposed to an alpha or beta release). But, it shouldn't be happening to you, as the latest core in the store is 3.4.5 currently (no -SNAPSHOT or build timestamp).