Unfortunately, using a 64bit floating point type in PDS3 is a little odd to see. Looks like ISIS doesn’t support it for ingestion. I think the max for ISIS3 is 32bit floating point. There is another issue we have seen with these labels by not setting the map_scale. Thus following this old thread, try this.
download both the label: https://pds-geosciences.wustl.edu/mro/mro-m-rss-5-sdp-v1/mrors_1xxx/data/rsdmap/ggmro_120_anom_100.lbl
and pixels: https://pds-geosciences.wustl.edu/mro/mro-m-rss-5-sdp-v1/mrors_1xxx/data/rsdmap/ggmro_120_anom_100.img
Edit the *.lbl, double check the math (the number of lines used below) but redefine MAP_SCALE from:
MAP_SCALE = “N/A”
radius (km) * PI / 2880 -->> 3396.0 * PI / 2880 -->>
MAP_SCALE = 3.70446133736 <km/px>
Now just load the updated ggmro_120_anom_100.lbl into ArcMap.
BTW, this file uses a Longitude range from 0 to 360, centered on 180. ArcMap can handle that, but it might have more issues or odd quirks as compared to using -180 to 180 longitudes.
To convert to GeoTIFF you can also use gdal_translate on the updated label too.
gdal_translate -of GTIFF ggmro_120_anom_100.lbl ggmro_120_anom_100.tif