Per the TQSL release notes as of version 2.5.3 (April 2020):
Minor Updates:
Ignore leading and trailing whitespace in ADIF values.
Ignore callsign fields (OPERATOR, STATION_CALLSIGN, OPERATOR_CALLSIGN) in ADIF files to work around defective logging programs.
When a Station Location has empty values, use the QTH details from the log being signed.