Winbox 3.11 running on Wine 5.0 and openSuse 15.2 does not find the Neighbor that is on the other side of a desktop switch. Three MikroTik routers show up on the Managed tab , but Refresh button leaves the Neighbors tab empty. Just downloaded Winbox again. Turned off Secure Mode. Can ping the router (6.49.1 updated today) from a terminal window and can log in via Webfig. Would prefer to use Winbox. Any suggestions? I can't find this situation when searching this forum.

I've only used winbox on windows, but you don't actually need to be able to find it in neighbours to login. you can just enter the address manually. If you can ping it you should be able to log in unless you have winbox disabled(/ip services) in the mikrotik you are trying to reach. Or you have the port blocked in either of your firewalls. which is by default 8291.

In regards to the neighbours not showing up:
check your "/ip neighbor discovery-settings" to make sure the interface facing your Wine is on the list.
Also make sure you are not blocking udp port 5678 on that interface, or your Wine.