I have x2 Sonoff Zigbee 2 USB3 Dongle Plus devices, one flashed as coordinator and the other as router ( CC1352P2_CC2652P_launchpad_coordinator / CC1352P2_CC2652P_launchpad_router). The coordinator worked fine and I could add devices easily. One thermometer kept loosing connection so I added the router… but it never showed up and the devices it was in between kept showing the same signal strength.
So I removed ZHA and went the Zigbee2mqtt route and the router showed up immediately.