Error: `fn` must be an R function with `conflict_prefer`

[DanChaltiel]

I cannot use the conflict_prefer function at all, while it works perfectly on my collegue's computer. Here is my call of the first example in the help:

library(conflicted)
conflict_prefer("filter", "dplyr")

Tthis throws this error:

[conflicted] Removing existing preference
[conflicted] Will prefer stats::filter over any other package
Error: fn must be an R function, not a primitive function

Here is the error trace:

> rlang::last_error()
<error>
message: `fn` must be an R function, not a primitive function
class:   `rlang_error`
backtrace:
 1. conflicted::conflict_prefer("filter", "stats")
 2. conflicted:::conflicts_register()
 3. conflicted::conflict_scout(pkgs)
 4. conflicted:::map2(names(conflicts), conflicts, superset_principle)
 5. base::mapply(.f, .x, .y, MoreArgs = list(...), SIMPLIFY = FALSE)
 7. conflicted:::is_superset(fun, non_base, base = base)
 8. rlang::fn_fmls(base_obj)
 9. rlang:::check_closure(fn)
Call `rlang::last_trace()` to see the full backtrace

> rlang::last_trace()
    x
 1. \-conflicted::conflict_prefer("filter", "stats")
 2.   \-conflicted:::conflicts_register()
 3.     \-conflicted::conflict_scout(pkgs)
 4.       \-conflicted:::map2(names(conflicts), conflicts, superset_principle)
 5.         \-base::mapply(.f, .x, .y, MoreArgs = list(...), SIMPLIFY = FALSE)
 6.           \-(function (fun, pkgs) ...
 7.             \-conflicted:::is_superset(fun, non_base, base = base)
 8.               \-rlang::fn_fmls(base_obj)
 9.                 \-rlang:::check_closure(fn)

> packageVersion("conflicted")
[1] ‘1.0.4’

> session_info()
- Session info ------------------------------------------------------------
 setting  value                       
 version  R version 3.5.2 (2018-12-20)
 os       Windows >= 8 x64            
 system   x86_64, mingw32             
 ui       RStudio                     
 language (EN)                        
 collate  French_France.1252          
 ctype    French_France.1252          
 tz       Europe/Paris                
 date     2019-09-06                  

- Packages ----------------------------------------------------------------
#[... a lot of packages...]

[dwhdai]

Any fix for this?