Summary: Inside Job bypasses the first piece of face up ice on a server, regardless of when that was rezzed.
Note: there are some effects that can cause to to encounter ice that hasn't been installed, such as Archangel, or that is installed on Awakening Center. These can also be bypassed with Inside Job if the server has no rezzed ice in front of it.
The specific rule for encountering ice is:
If the approached piece of ice is rezzed after the Corporation has the
opportunity to rez cards, then the Runner encounters it.
The confusion here probably comes from the fact that "rezzed" is both an adjective and a verb, depending on context. In this particular piece of rules, we are dealing with the adjectival form. Let me translate:
If the approached piece of ice is [face up] after the Corporation has the
opportunity to [turn cards face up], then the Runner encounters it.
If the ice is face up, it is encountered. This includes ice that has been turned face up on previous runs/turns. The reason for the extra bits of the sentence is to clarify that even if the ice was rezzed just now, it is still encountered (see the run structure chart at the end of the rulebook).
If you want to stop Inside Job, try effects that prevent bypassing, like the ability on Guard.