Welcome to Shipspotting, MrBlond.
The absence of ports in Montenegro, and one or two other countries has long been a concern (as well as many indicidual ports in other places), but hitherto we have not been able to edit the list installed by the former IT managers decades ago. I remain hopeful that, as part of the upcoming site refresh (which is going slower than expected during this difficult year), we will be able to do so in future. When I have news on this, I will comment onhttp://forum.shipspotting.com/index.php/topic,16559.0.html
For Montenegro, I have on my list to include also Tivat, Bijela and Bar.