Similar to BUG-000114646 (Add Join in ArcGIS Pro yields the wrong data when input as view or layer with a query), Join Field is yielding the wrong data when the inputted join table is a layer with a query. Instead of joining from the subset of data in the query, it is joining the first value from the whole table. A temporary workaround is to export the queried layer into a new feature class and re-run the join, but it should be able to join from the queried table directly.
BUG-000114646: Add Join in ArcGIS Pro yields the wrong data when in.. (esri.com)
Are you using ArcGIS Pro 2.7?
Yes, I'm using 2.7, but this error is occurring with the Join Field function rather than the Add Join function.
You might want to open a case with Tech Support then.
Submitted! Just curious if anyone else experienced this issue.
Your workaround of making a standalone subsample prior to the join would have been my preference to begin with. It compartmentalizes steps so they can be easily replicated.