The LO SQL parser does not accept:
because it expects some operator after "foo.qux". But this syntax (and also "WHERE NOT foo.qux") is accepted by at least PostgreSQL when foo.qux is a boolean column.
Investigate whether this syntax is standard SQL or PostgreSQL-specific (or maybe not standard, but widely supported) and whether it would be a good idea to support it in LO's SQL parser.
Adding self to CC if not already on
Dear Lionel Elie Mamane,
This bug has been in ASSIGNED status for more than 3 months without any
activity. Resetting it to NEW.
Please assigned it back to yourself if you're still working on this.