Welcome to the forum evansorrell.
I'll try and help but this could be a tricky one (or it might be very simple, we'll see).
Firstly, which OS are you using and which version of Scribus? (That can make a big difference.)
Next, what exactly do you mean by "stopped working"? That can be interpreted a number of ways with similar symptoms but different solutions.
For instance, have you been importing images just fine until you got to a point in time where the images were no longer being put in the frames even after you OK'd the Import Image dialog? Can you please explain the exact work-flow you were using around when things started to go wrong (both before and at the point of change)?
Also, can you check the following things:
1. You haven't moved/renamed the document or images files to different folders or machines.
2. All of your images are on layers that are both visible and exportable.
3. Menu "View -> Show Images" is checked.
4. With a frame selected, menu "Item -> Preview Settings -> Image is Visible" is checked.
5. Your images are "clean" and don't have any weird metadata or colour information in them. (Use GIMP to load and export them to clean them.)
6. It shouldn't be an issue but can you check your free memory status?
7. Are you using images on any kind of attached storage such as network drives or similar?
I think that's enough to go on for now. If you can make the suggested checks and supply the necessary information we can move forward (unless you have enough info' to fix things already).