Current Import Won't Update

I recently purchased a new iMac and transferred my data across through Time Machine. Ever since my LR will not update the "Current Import" part of my catalogue. Each time I upload new images (pretty much daily), it continues to load the images I did at a shoot several weeks ago and is now labelled "Previous Import". I have tried rebooting LR with default settings etc but keep coming up short. Would prefer to not have to start a whole new Catalogue if possible. Any thoughts on how to fix this?