I run Mac OS High Sierra LibreOffice 6. After connecting to a postgresql database I send a SQL query. If there is an error the return of the server is promted. Ok, if the query executes (I can see it afterwards) the whole libreoffice freezes completely without responses. This holds fo any SQL query I tried even the simplest like SELECT * FROM “Table1”
What type/version of connector are you using?
postgresql I guess
It seems you can see and hopefully modify tables without a problem.
Have just verified connection on Mint 18.2 using Lo v188.8.131.52. Two tests - Native connector (PostgreSQL comes with Base) and a JDBC connector v42.1.1 from PostgreSQL and both work without problem for tables, queries and forms.
You may want to try a JDBC driver.
If still having a problem check Bugzilla for existing problems in this area. Cursory glance doesn’t show any. Be prepared to give details and possible sample when filing.