What would cause the garage door remotes in your condo association to open and close one condos garage door and not work on their own for a period of about 5 hours then back to normal?

You do not state whether this is a regular occurrence, or whether now, everything is back to normal.

You can ask your preventative maintenance staff to work with the remotes to verify that they both use the appropriate codes, that the batteries are sufficient to operate the remotes and so forth.