value parameter in tbl_summary doesn't work on an empty category

[JeremyPasco]

Expected behavior:

Setting the value parameter of tbl_summary on a category should display only this category, even if this category has a null count.

Actual behavior

On categorical variables, setting the value parameter on a non represented category does nothing.

Reprex

library(tidyverse)
library(gtsummary)

x <- trial %>% 
  transmute(
    trt = fct_expand(trt, 'Drug C')
  )

tbl_summary(x) # display all categories: OK
tbl_summary(x, value = trt ~ "Drug A") # display only Drug A: OK
tbl_summary(x, value = trt ~ "Drug C") # display all categories: wrong

^{Created on 2021-02-11 by the reprex package (v0.3.0)}

By this third summary, I expected one row with : Drug C 0 (0%)

[ddsjoberg]

😱 thank you so much for the report!