dplyr `case_when()` trouble with NA

library(tidyverse)
df <- tibble(ID = c("ABC", "EFG", "HIJ", "KLM", "NOP", "QRS"),
             Date = as.Date(c("2019-01-03", "2019-01-08", 
                              "2019-06-09", "2019-06-11",
                              "2019-08-12", "2019-08-21")))
#> # A tibble: 6 x 2
#>   ID    Date
#>   <chr> <date>        
#> 1 ABC   2019-01-03    
#> 2 EFG   2019-01-08    
#> 3 HIJ   2019-06-09    
#> 4 KLM   2019-06-11    
#> 5 NOP   2019-08-12    
#> 6 QRS   2019-08-21 

Let's start with the data frame above. What I want is shown directly below. The first two line items in the data frame satisfy the conditions in my case_when() statement, and are populated with "fizz" and "buzz". The remainder is populated with NA.

df %>% 
  mutate(col3 = case_when(ID == "ABC" & Date == as.Date("2019-01-03") ~ "fizz",
                          ID == "EFG" & Date == as.Date("2019-01-08") ~ "buzz"))
#> # A tibble: 6 x 3
#>   ID    Date       col3 
#>   <chr> <date>     <chr>
#> 1 ABC   2019-01-03 fizz 
#> 2 EFG   2019-01-08 buzz 
#> 3 HIJ   2019-06-09 NA   
#> 4 KLM   2019-06-11 NA   
#> 5 NOP   2019-08-12 NA   
#> 6 QRS   2019-08-21 NA 

Yet when I try to explicitly tell the case_when() function to populate the remainder of the data frame with NA I get the error shown below? Am I not utilizing TRUE ~ NA in the correct fashion?

Doesn't the TRUE ~ _XYZ_ argument tell the function to populate any condition not satisfied by conditions above with _XYZ_?

df %>% 
  mutate(col3 = case_when(ID == "ABC" & Date == as.Date("2019-01-03") ~ "fizz",
                          ID == "EFG" & Date == as.Date("2019-01-08") ~ "buzz",
                          TRUE ~ NA)
#> Error: unexpected ',' in " 
#> ID == "EFG" & Date == as.Date("2019-01-08") ~ "buzz","