I am using ArcGIS pro 2.8
1. There is a simple task I need to do, like joining a csv to a layer based on a common field, and then export it to save all the information in a new layer. It was really a simple task in ArcMap, but I don't know why after exporting the joined-up layer (selected layer from a shapefile) and the csv table, all data belonging to the csv table are turned into 0s in the exported output layer. That was my first issue.
2. Then I thought, ok maybe I can create a new field in the selected layer, and update it with the information from the csv table. I get the message below saying the column specified does not exist!! Well, I am updating SCI_Score column based on SCI column coming from the csv table; both columns have Double type. They are clearly both there in the joined up layer.

Anybody knows why this is happening?