it depends what you definition of “data” is.
Sometimes the contours of your spectra won’t be drawn, if the paths to the spectrum files are incorrect. You can always go to Spectrum / Validate Paths (VP for short) and check them (they’ll be red if they are wrong) and correct them if necessary (they will turn green as soon as they point to valid file).
This is a slightly separate issue from the actual data not being in the project - that would mean that the sidebar is totally empty with nothing in it. When you expand Spectra or other parts of the sidebar do you see anything?
So perhaps worth checking whether the issue is that you can’t see the contours, or whether you can’t see any items in the sidebar. If you send us the project, we can obviously check whether there is data in the project in terms of items in the sidebar (we’re also happy to look through the actual xml files and see what is going on there). But it’s much harder for us to check the spectrum contours/files unless you send us those as well (which is usually rather a lot of data).