group_by then mutate not working

[pf1122]

I have suddenly run into the issue where any time that I specifically try to use group_by and then mutate, the output is only NAs. If I run the same exact code on a co-worker's workspace, the output is as expected. All other functions that I use are working normally. I have tried detaching and reloading libraries. I have tried using a new workspace and recreating all data frames, and code that previously worked for me no longer has the correct output. I am using R version 3.4.4. Would appreciate any help! Here are examples of code that previously worked fine and now returns only NA for all output.

ventfile <- ventfile %>% 
  group_by(mrn, hsp_account_id) %>% 
  mutate(fourdays=ifelse(max(Interval)-min(Interval) > 95,1,NA))

and

ventfile24 <- ventfile %>%
  group_by(mrn, hsp_account_id) %>%
  filter(row_number()<=24) %>%
  mutate(SetRR2=mean(`Set Respiratory Rate`))
type or paste code here

[mara]

Could you please turn this into a self-contained reprex (short for reproducible example)? It will help us help you if we can be sure we're all working with/looking at the same stuff. You're not far from that now, except no one else has ventfile. You can easily add a small sample of the actual file (if you can't recreate the behaviour with built-in data) in various ways, but I personally like the datapasta approach best.

install.packages("reprex")

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