The biblatex manual states that the entry type "software" usually doesn't have a driver and falls back to "misc" as its driver. With the IEEE style this doesn't print URLs. Therefore: is there any way to remap software to use the "online" driver as its fallback?
You can use
to use the
@online driver for
@software types. You can learn a bit more about this command in What exactly is the relationship Biblatex refers to as an alias of an entry type? And how should the formatting of aliased entry types be configured?