Hi Paul, thanks for you reply. Below is the part of my code generating the map widget. OpenStreetMap is the default map tile so I did not claim it explicitly, I tried to replace the 2nd line with yours (with "%>%" to the end) but it did not work either.
m <- leaflet(f171028_sub) %>%
addTiles() %>% # Add default OpenStreetMap map tiles
addCircles(lng = ~ lng, lat = ~lat, popup = ~popup, radius = 0.25, color = ~pal(disp2), opacity = 0.75) %>%
addLegend("bottomright", pal = pal, values = -15:15,
title = "Ground Movement (mm)",
opacity = 1
)