Hey,
to know wether the underlying issue is related, It would be great if you can also try to open Event Capture while looking at the javascript console of your browser.
Which operating system are you running the server on?
Firstly, you should consider upgrading from PostgreSQL 9.5 to any newer version - I would recommend 11.2 (but anything from 9.6 onwards is significantly faster than 9.5 in terms of DHIS2 processing due to more efficient btree indexing).
Secondly, since you are using Tomcat 9, have you changed the configuration file “server.xml” in the tomcat “conf” folder to ignore the ban on using square brackets introduced from Tomcat 8.0.35 onwards?
Like this:
Check that segment in the server.xml file, and add the relaxedQueryChars=“[]” instruction if it is not there.