I think therefore you will have to handle the dates as integer triples.
(tb <- tibble::tribble(
~dateissue,
13990508L,
13990507L,
13990506L,
13990505L,
13990504L,
13990501L,
13990431L,
13990430L,
13990429L,
13990428L,
13990425L,
13990424L,
13990423L
) %>% mutate(
solar_year= floor(dateissue/1000) %>% as.integer(),
solar_month= floor((dateissue - solar_year*1000)/100)%>% as.integer(),
solar_day = dateissue- solar_year*1000 - solar_month*100%>% as.integer()
))