Masked raster is completely black when reprojecting and masking in GRASS GIS

Question

I have a global raster of railways networks in Mollweide CRS (resolution 1000x1000) and I want to reproject it to Europe (EPSG:3035), crop it to Europe, and change the resolution to 30x30 km (0.25°). I downloaded the raster map from here https://datadryad.org/stash/dataset/doi:10.5061/dryad.3tx95x6d9 (folder Human_footprint_pressure_layers, size 438.71 MB, file railways.tif).
What I would usually do would be to reproject it (externally from GRASS GIS) using gdalwarp, first to EPSG:4326 (as I still have this problem and, apparently, first transforming from EPSG:54009 to EPSG:4326 and then do the rest works) with:

gdalwarp -overwrite -t_srs EPSG:4326 -tr 0.25 0.25 /mypath/railways.tif /mypath/railways_WGS84.tif

Then I access GRASS, enter my EPSG:4326 mapset and load the file:

grass /mypath/grass/4326/PERMANENT 
g.region -p res=0.25
r.in.gdal --o input=/mypath/railways_WGS84.tif output=railways_WGS84

Then I'd switch mapset to my EPSG:3035 one, create a raster mask of Europe, and reproject from EPSG:4326 to EPSG:3035, having therefore the railways_WGS84 reprojected and clipped to Europe:

g.mapset mapset=PERMANENT location=3035
g.region -p raster=EU_3035 res=30000
r.mask --o raster=EU_3035
r.proj --o location=4326 mapset=PERMANENT input=railways_WGS84 output=railways_3035
r.out.gdal --o input=railways_3035 output=/mypath/railways_3035.tif

This creates a raster map with desired resolution and CRS but 255 colour categories, and the whole raster looks the same (it doesn't have different values depending on the part of Europe), like this:

I think what is failing here is the masking part, because until the reprojection from railways_WGS84 to railways_3035 and before the masking part, the files look fine, like this:

I tried also r.mask.rast in QGIS but produced the same result:

processing.run("grass7:r.mask.rast", {'raster':'mypath/EU_3035.tif','input':'mypath/railways_3035.tif','maskcats':'1','-i':False,'output':'TEMPORARY_OUTPUT','GRASS_REGION_PARAMETER':None,'GRASS_REGION_CELLSIZE_PARAMETER':0,'GRASS_RASTER_FORMAT_OPT':'','GRASS_RASTER_FORMAT_META':''})

I am using GRASS GIS 7.8.7 from a Linux server and QGIS 3.28.2 from a Windows 10 local machine.