A reproducible example, called a reprex FAQ: What's a reproducible example (`reprex`) and how do I do one? is pretty much required to give an accurate answer, @williaml says.
The hardest part can be the data, but there's an approach that helps. First, not all the data is needed. Second, you can run
dput(dataset1)
# cut and paste
dput(dataset2)
# cut and paste
Screenshots are almost never helpful. The most I can see here is that there may not be a key field to join by.