Rule not picking up the Source/Download value

I have a rule that has stopped working. It checks whether a file was downloaded from a file-sharing service and labels it accordingly. Subsequent rules handle filing.
NOTE: for clarity I have moved the rule and some sample files to a separate folder.
SAMPLE FILES

INFO PANELS

NOTE: I forced the entry for #3 using a command line app to set the Source, in case there was an issue with the downloaded example (#1) or much earlier version (#2)
THE RULE

RESULTS
File #1, recently downloaded

File #2, downloaded a couple of years' ago

File #3, this is #2 but with Source reset

LOG FILE ENTRIES
2019-12-19 10:51:39.842 hazelworker[97238] Processing folder Test
2019-12-19 10:51:41.861 hazelworker[97238] Done processing folder Test
THE REALLY WEIRD THING
The rule status report says the files match the rule …

NOTE: for clarity I have moved the rule and some sample files to a separate folder.
SAMPLE FILES

INFO PANELS

NOTE: I forced the entry for #3 using a command line app to set the Source, in case there was an issue with the downloaded example (#1) or much earlier version (#2)
THE RULE

RESULTS
File #1, recently downloaded

File #2, downloaded a couple of years' ago

File #3, this is #2 but with Source reset

LOG FILE ENTRIES
2019-12-19 10:51:39.842 hazelworker[97238] Processing folder Test
2019-12-19 10:51:41.861 hazelworker[97238] Done processing folder Test
THE REALLY WEIRD THING
The rule status report says the files match the rule …
