This is there car. ...'there' is not underlined in blue.
I use the LibreOffice plugin on Debian Linux. Other errors, such as unwanted word repetitions seem to be picked up fine by Languagetool.org spell-checker.
Languagetool - latest version, downloaded and installed 3 days ago.
LibreOffice version 5.2
LightProof grammar check is deactivated in LibreOffice