Apparently it can be a nightmare. 20 hours at least once. So bad the government was passing out food and water.
Its still worth the effort with the right help. The good guides and drivers know the best times of day and how to access the cameras at the two crossings and chose the better of the two.
As the problem rests with the EU state i dont know if Croatia / Bosnia is any better.
I wouldnt let this deter visiting Bosnia or Montenegro, but I would get assistance in planning crossings. PM and I can give you a name, or search the forum as there are other possibilities as well.