Goto file/class is broken in 2018.1.4 Ultimate

When using CTRL+N (or CTRL+SHIFT+N) to either "goto class" or "goto file" the floating window opens, I can enter a (partial) filename and one or more searchresults appear in the list. But as soon as I click on one of the results the window just closes and nothing happens! (file is not presented to me)

Running (L)Ubuntu 15.04 on Virtualbox.

I installed IDE 2018.1.4 and chose to import the settings of 2017.1.6 which is still on the same machine and functioning properly in this regard.

This issue makes the IDE totally crippled in my opinion, as I make use of these shortcuts very frequently on a daily basis!

Searched in the issues, couldn't really find something similar.

Anyone got a clue?