I am thinking of this way. when turn on netlock, all current user will became whitelist, then you can add/remove user between whitelist and jail. this can be done by enable user access , or turn off user access.
what size of the network were you scanning? fast scan usually can show difference in size bigger.
For C class network, normal scan should finish in 10 seconds when first scan, followed scan might finish in 2 seconds as some of the results from cache.
Fast scan should finish scan C class network in 1 second.
so during small size network, you might not tell difference.
fast scan , when you repeat scan over 12 seconds and previous scan still in progress. the scan request will be ignored. is that the your “turned off” case?