leaflet - point on the map moves when zoom in and out - r

Question

I used leaflet package to creates a map widget, and then added two layers with the function addMarkers(). However, I found that the points on the map change their positions when zoom in and out. The relative scripts are as following:
First, create a function pchIcons with r shapes in leaflet
pchIcons <- function(pch = 0:14, width = 30, height = 30, col = 1:15, ...) {
pchLength <- length(pch)
pchFiles <- character(pchLength)
# create a sequence of png images
for (i in seq_len(pchLength)) {
pchTempFile <- tempfile(fileext = '.png')
png(pchTempFile, width = width, height = height, bg = 'transparent')
par(mar = c(0, 0, 0, 0))
plot.new()
points(.5, .5, pch = pch[i], cex = 1.5, col = col[i], ...)
dev.off()
pchFiles[i] = pchTempFile
}
pchFiles
}
Then create a base layer with Paris' position, and add two layers, each layer represents one group.
baseLayer <- leaflet(zero) %>%
addProviderTiles("Stamen.Toner") %>%
setView(posParis[["lng"]], posParis[["lat"]], zoom = 12)
addZeroLayer <- baseLayer %>%
addMarkers(popup = paste(paste(zero$Code, zero$Ecart),
zero$Address,
sep = "<br/>"),
lng = as.numeric(zero$Long),
lat = as.numeric(zero$Lat),
icon = ~ icons(
iconUrl = pchIcons(rep(magasinEcart[1], nrow(zero)),
40,
40,
col = colorZero,
lwd = 2)
),
group = '0')
addOneLayer <- addZeroLayer %>%
addMarkers(popup = paste(paste(one$Code, one$Ecart),
one$Address,
sep = "<br/>"),
lng = as.numeric(one$Long),
lat = as.numeric(one$Lat),
icon = ~ icons(
iconUrl = pchIcons(rep(magasinEcart[2], nrow(one)),
40,
40,
col = colorOne,
lwd = 2)
),
group = '1')
Next, add UI controls to switch layers on and off with addLayersControl() and add legend with addLegend().
mapTourist <- addOneLayer %>%
addLayersControl(overlayGroups = c('0', '1'),
options = layersControlOptions(collapsed = FALSE)) %>%
addLegend("bottomright",
pal = colorFactor(brewer.pal(9, 'Set1')[3:4],
unique(magasinBaseComp$Ecart)),
values = names(magasinEcart),
title = "Ecart",
opacity = 1)
Finally, we can find that when zoom in or out, the points on map moves (as screenshots show).
Does someone know what's the problem and how could I solve it? Any idea is welcomed!