When looking at an Experiment under 'Student Data' | 'Find and Manage, why does the 'Experiment Status' column show a Question Mark?

The '?' icon in the Experiment Status tab is caused when some members of a Group (2 or more Students) within LabTutor edit the Experiment separately in LabTutor Online. Since the Experiment is neither wholly in Online nor wholly on-site, the '?' appears.
For example, Student A, Student B and Student C access the ECG and Peripheral Circulation Experiment, and record and analyse their data. Student C then logs in to LabTutor Online at home to complete the report. This will result in the '?' icon, as Student A and B are still working on-site, and Student C is now editing the Experiment in LabTutor Online. If Student A and B logged in and edited the Experiment in Online, the '?' would become the LabTutor Online symbol.
As with any icon in LabTutor, mousing over the icon will provide further detail:
servlet.ImageServer?id=015w0000001IwED&oid=00D20000000HncM