cat_plot showing same confidence intervals for all data points (interactions package in r)

Question

I am using the cat_plot function from the [interactions]https://interactions.jacob-long.com/reference/cat_plot.html package to plot a 2-way interaction between two categorical variables.

I have the following syntax:

set.seed(123)

cat_1 <- rep(c("A", "B", "C"), length.out = 150)
cat_2 <- rep(c("X", "Y"), each = 3, times = 25)

outcome <- round(rtruncnorm(n = 150,a = 1, b = 7,mean = c(5.7, 6.8, 3.1, 2.4, 6.9, 5.9), sd = c(1.8, 0.9, 1.5, 1.4, 1.1, 1.6)))

df <- data.frame(cat_1, cat_2, outcome)

glm_2way <- glm(outcome ~ cat_1*cat_2, data = df)

cat_plot(glm_2way, pred = cat_1, modx = cat_2, interval = TRUE,
         colors = "Rainbow")

Which gives me this graph:

Which shows exactly the same error bars for all the data points. The example given in the vignette with the diamonds package uses exactly the same syntax, cat_plot(fit, pred = color, modx = cut, interval = TRUE) but shows the correct error bars. What am I doing wrong?