This can happen when there are gaps in instrumentation of the agent. For instance, if there is a host or process downstream that is slowing things down, but there is not a OneAgent on that host, Dynatrace would not be able to correlate the root cause back to the specific issue. Do you have any specific examples you can provide? Or know of any gaps in implementation?
If there is no root cause generated for the problem does this also mean that the visual resolution path is not generated as well? I am seeing that for problems with no root cause, there also seems to be no visual resolution path.