A scan that never starts is almost always the app refusing to run rather than the app being broken. It holds back when it cannot prove the session is good, because a scan on an unproven session produces junk data or gets the account flagged.
Work through these in order
1. Confirm you are actually signed in
Open the built-in browser and look at Facebook. If you see a login page, a security checkpoint, or a "we have detected unusual activity" interstitial, that is your answer. Clear it manually in the browser first. The app cannot click through a checkpoint for you, by design.
2. Check whether Facebook is asking for a checkpoint
Facebook will quietly gate an account after a password change, a new device, or a new location. The app will not scan until that is cleared because anything it collected would be incomplete.
3. If you use a proxy, test it
A proxy that is refusing connections will stall a scan before it produces a single result. Turn the proxy off briefly and try a small scan. If it runs without the proxy, the proxy is your problem, not the app.
4. Start smaller
If you are scanning a very large group, try a small one first. A scan that works on a small group and stalls on a large one is a different problem from a scan that never starts at all, and knowing which one you have saves a lot of time.
What to send us if none of that helps
The single most useful thing is the exact wording on screen. "It is not working" takes several messages to turn into a diagnosis, whereas the literal message usually identifies the cause immediately.
- the exact message or a screenshot of the whole app window
- your version number from the top of the app
- whether it is one specific group or every group
- whether it worked before, and roughly when it stopped
- whether a proxy is in use
"It worked until Tuesday" is genuinely useful information. Facebook changes things, and a date tells us where to look.