de_mean() returns warning message with more than two variables

[Francisco Wilhelm]

I'm trying to center a set of variables; sjmisc::de_mean() returns a warning message with more than two to-be-centered variables. Returned variables look fine though.
For example, trying such a code:

data(efc)
efc$ID <- sample(1:4, nrow(efc), replace = TRUE) # fake-ID
de_mean(efc, c12hour, barthtot, c83cop2, grp = ID)

returns

Warning message:
In colnames(x_gm) == cn :
longer object length is not a multiple of shorter object length

Lieben Dank
Francisco