Learning Instructors showing as unavailable but they are available

We have instructors setting up courses and offerings but when they try and add the activities its saying that they are unavailable to complete the course as they are elsewhere, even though they know they are not offering any other courses at the times they have set up. I cant seem to find much on knowledge, and I cant work out if there is a way to see an instructors diary to see why they may be showing as unavailable. We have not adopted redwood for the back office in learning but have switched to redwood for customers