I can confirm same issue on Ubuntu 18.04 - probably a kernel change in the higher 4.15+ kernels that affect WINE APIs to the network stack (i'm currently running 4.18.5).
I keep a windows VM installed with VIrtualBox as a just-in-case for situations where I absolutely need mac learning, as it can be hit and miss on WINE even pre-18.04.
It's not something that Mikrotik are likely to be able to fix, as Winbox is a windows application and running on WINE is not officially supported. All other aspects of Winbox work OK for me though.
Edit: Just saw you cant connect by IP either, that is the weirder part - I'd say its maybe firewalled off somewhere for 8291? Check your filter rules etc. Normal connectivity of Winbox works fine for me its just neighbor discovery that is not working for me.
Hey Joe
I have a Windows environment so its not much of a hitch if winbox doesnt work in Ubuntu, but I am trying to make use of Ubuntu to make myself more handy with Linux. I can work with VMs. But Its just very complicated and involves extra steps (I'll switch to VMs eventually if nothing works).
I enabled firewall also and explicitly allowed 8291, but still it doesnt work. Moreover, I cannot get to the router via browser also.
If it is getting DHCP I don't think there is some issue with IP config or routing, right?