This article was written at a time when a version of TQSL was released that began validating location data when comparing your log to your certificate. While newer versions of TQSL have been released that have made this validation less impactful, this article still describes what you should to to troubleshoot errors you receive when uploading your QSOs to LOTW.
DO make sure that you are using the most recent version of TQSL and Ham Radio Deluxe. These are the versions that either developer groups will be able to support.
On 6-April, 2020, a new version of TQSL was released (v2.5.2; and v2.5.3 following that). This new version includes a new "feature" that prevents people from uploading inaccurate data to LOTW. In particular, the release notes say the following: "When the log states that the US State is one value but the Station Location gives another, TQSL rejects that QSO." Unfortunately, the TQSL certificate spells out the entire US State name (e.g. "Texas"), but their system is expecting the 2-character abbreviation for US State (e.g. "TX"). Because of this, we're getting reports of LOTW uploads being rejected when things like the US State do not match.
In HRD Logbook's "logfile", you can see the response from TQSL. It will tell you what's wrong with your data. You can see this logfile from within Logbook by clicking View > Logfile. (This requires that a LOTW upload attempt was made just prior to viewing the logfile.)Here's an example:
Here is a link to a more complete explanation about the changes in TQSL and what you need to do in Ham Radio Deluxe to recognize and correct data entry errors in your log:
Beyond providing this guidance specific to Ham Radio Deluxe, we're not in a position to provide further guidance specific to TQSL.
For matters related to TQSL and LOTW, please refer to the LOTW help ticket service found here: http://www.arrl.org/lotw-help-ticket