First, I like "holding out" rather than waiting -- it implies some difficulty in remaining steadfast, some pressure to change.
Second, I wouldn't say "the issues are external" necessarily. A Steadfast MC in Mind or Psychology can certainly be seen to have internal issues. Think of a manipulative MC who sticks with that approach through to the end. Or one with a fixed attitude, say a bigot.
A Steadfast characters' Problem is often best seen as their "drive" (though it is still problematic for them). And their Solution is best seen as their "demotivator". Here's a thread on that:
How much you bring the Demotivator into play is up to you. In some stories it might come into it very little.
Motivated by their Problem, a Steadfast character sticks with their Response, continuing to see their Symptom as something that needs to be addressed.
"Successful resolution" depends on your story's Outcome and Judgment. If you have a Success/Good triumphant ending, you're saying that the MC was right to remain steadfast -- they were satisfied in the end (Judgment) and somehow helped bring about Success (even if they weren't the Protagonist, they should have some impact on achieving the Goal).
Other types of endings you're saying something else, like a Failure/Good might be "it was good for the MC personally to remain steadfast, but perhaps they could have helped achieve the Goal if they'd changed their perspective".
Does that make sense? If you let us know your Outcome and Judgment we could see how those fit in.