Error with bca CIs for ordered outcomes

[dominix88]

Mediate returns NaNs for the CIs if I run a model with ordered outcomes and the bca option. Here a reproducible example:

library(mediate)
library(MASS)

dv <- sample(1:4, size=200, replace=TRUE)
m <- sample(1:4, size=200, replace=TRUE)
t <- sample(0:1, size=200, replace=TRUE)

ex.dat <- data.frame(dv,m,t)
ex.dat$dv <- as.factor(ex.dat$dv)
ex.dat$m <- as.factor(ex.dat$m)

med.m <- polr(m ~ t, data = ex.dat)
summary(med.m)

out.m <- polr(dv ~ t + m, data = ex.dat)
summary(out.m)

out.ord <- mediate(med.m, out.m, treat = "t", 
                    mediator = "m", sims = 100, 
                    boot = T, boot.ci.type = "bca")
summary(out.ord)

It produces an output, but the CIs are missing.

It returns the following warning:

Warning messages:
1: In qnorm(z.inv) : NaNs generated
2: In qnorm(z.inv) : NaNs generated
3: In qnorm(z.inv) : NaNs generated
4: In qnorm(z.inv) : NaNs generated
5: In qnorm(z.inv) : NaNs generated