How large is the unadjusted range (I assume the unit of value is $/unit)?
While your review SOW can affect exactly how you handle this, the first question is, is the value indication credible as presented; i.e., does the number make sense based on what you are required to review?
If it does make sense, then the issue is (in my opinion) poor application of the methodology used in the reconciliation of the indicated value. If it doesn't make sense, then the reconciliation is not the primary issue.
I have five apartment buildings and with no adjustments, the $/unit ranges between $250k to $265k. They are all overall simialr; unit mix, location, condition, etc. Such a spread would not be unusual in such a scenario.
Perhaps no one sale is significantly superior than any other one. What would be the logical expectation in such a scenario? Assume market conditions have already been addressed, the expectation would be that the value be somewhere in the middle because there is, based on what the report is indicating, no reason to go to one end or the other.
The mistake the report has made is in its explanation of its rationale. The methodology of reconciliation requires the appraiser to apply his/her judgment and what the report implies is that it substitutes a rote calculation for that judgment.
Had the report said something like,
"In the grid analysis, no adjustments were necessary. Each comparable is similar to the subject and any one is as good and reliable an indicator of value than another. In my reconciliation of the value indication by sales comparison approach, I considered each comparable equally and reconciled to the mid-point of the range."
Would there be an issue? There wouldn't be one for me (assuming I agreed that the comparables required no adjustments and the value indication was credible).
In my review work, I'd talk to the appraiser and point out the issues I see with implying that the reconciliation was formulaic-driven rather than judgment-driven, and suggest an alternative statement in the reconciliation and give my reasons. The appraiser could agree or disagree. If they agree, great. If the disagree, then I'd note the disagreement in my review and state that notwithstanding the application of a rote-calculation, the indicated value concluded in the sales comparison approach is credible.
And then I'd move on.
Like I say, your review SOW may not allow that.
Good luck!