Anyone have experience with a “field appraisal?”

[William Thorn]

I’m selling a 4 unit building in San Diego and it was due to close on Monday. The buyers lender just came back and said they need to do a “field appraisal.” I assume it’s because they have some sort of issue with the appraisal but I have never had this issue. Does anyone have experience with this and what was the outcome? Thank you.