Is this normal behavior? I notice wifi works when I plug the drive into power directly, but when I plug it into my computer the wifi doesn’t seem to broadcast.
Yes, that’s normal. When it’s connected via USB, the internal system of the MPW shuts down so that the host computer (your desktop) can “own” the disk.
If you want to simply charge through your PC, but don’t need to access the data via USB, you can use a USB charge-only cable.