Hi,
I am trying Locus Free and can get Network location working. Battery saving mode of location is enabled in system settings and works works flawlessly with other apps - weather widget and Here WeGo. Locus however, shows my position only if there is GPS signal. If GPS is not turned on Locus shows a massage that "Getting location using GPS or WiFi is not turned on in the system settings", although it is on (in battery saving mode), Wifi is on (I have changing ads and can download/view maps). My guess is that without GPS on in system, locus does not see the correct status of location settings (i.e. that they are in battery saving). I have also checked locus permissions and they are set identically as those of Here WeGo.
Regards
It does work on my phone, as long as you are close enough to wifi and/or mobile networks (always more than one).
The icon in the top bar is orange for network location and green when GPS is on.
And yes, that Locus announcement is a bit strange.