You can see the scanning queue on http://127.0.0.1:9524 on the server.
Lastseen: last time lansweeper scanned the computer without a problem (rpc, access denied, ...)
lasttried: last time lansweeper tried scanning the computer.
If there are any errors you can see them in the error tab on the computer webpage.
What is Eventlog Scanning:
Event log which is I can find under "Computer management" -> "System Tools" -> "Event Viewer"
Correct
Another thing that confuse me: in section "scanned computers" column "last seen" does not have any date more recent then 2 weeks.
Is the lansweeper service still running?
Do you see any errors on the scanned computers?