Symptom: sample_n does not work and gives an error
The error would look like
Size must be less or equal than xxx (size of data)
How to fix.
If your data frame is
Grouped By like below, it suggests one of your group has less rows than the sample size you specified.
So you might want to ungroup your data frame before you run
sample_n. If you do want to sample for each group, pass less number of the argument.