If it is an agenda in a new committee, the agenda has most probably been transfered to Prepare, but you have not added yourself to the new committee yet. Read about how you join a new committee.
You can also check if the agenda has been transfered to Prepare in the first place. Take contact to the responsible IT manager in your organisation and make them check in the source file, where files are transfered from, is empty.
If the upload client source folder has been emptied, it may be due to an error while importing. Contact First Agenda Support at firstname.lastname@example.org for further investigation.