Cisco GLC-LH-SM don’t support DOM, however mikrotik SFPs with DOM function. I guess that is the reason, so just try and test anther model such as GLC-LH-SMD.
I am having the same issue with other SFP modules with copper interface, so I don’t think the issue is with DOM - they work fine with RB2011 and CCR, but don’t work with RB3011 (RB reports rx-lose flag). I’ve opened a ticket with MT support, I suggest you do the same. I hope they can provide some info soon.
Was there any outcome or feedback from MT?
I experience the same issue, when I wanted to migrate from RB2011 to RB3011.
My SFP DSL Modem works in the RB2011 but reports “RX Lose” and “no link” with the RB3011.