The easiest way I've got to reproduce:
- clean userdir, recent dev build
- install jVi, first the jVi update center, then jVI
  http://plugins.netbeans.org/plugin/38914/jvi-vi-vim-for-nb-update-center
- open a java file
- press "ESC" key
Observe the editor window should flash

or
- press "i"
  go into input mode, note cursor changes shape from block to vertical bar
- press <ESC>
  this should exit input mode, cursor should go back to block
Observe nothing happens

Can get out of input mode by mouse click on the editor, cursor goes back to block.

The jVi option "debug key strokes" can be turned on and every key that jVi sees is output, shows up on console and messages.log. You can turn this on at
Tools>Options>jViConfig>Debug. set it to INFO will do it.

Observe in output that the ESC key never gets delivered to jVi.


Product Version: NetBeans IDE Dev (Build 201505260001)
Java: 1.8.0_40; Java HotSpot(TM) 64-Bit Server VM 25.40-b25
Runtime: Java(TM) SE Runtime Environment 1.8.0_40-b26
System: Windows 7 version 6.1 running on amd64; Cp1252; en_US (nb)