if it is a known issue, you'll find it in the solidworks kb at customerportal.solidworks.com
a screenshot of your model and results might be helpful here. ideally pointing out which ones are reporting and which aren't. the model would be even better.
assume you've already tried building a simple model to check whether this is model specific and that you've tried a brand new study to make sure it isn't just a bad study and tried some other loads to see if it is setup specific? if you start simple and build up from a new study (adding peices by drag and drop and including them), you'll find what change causes the issue or isolate the beams that are the problem