Product Version = NetBeans IDE Dev (Build 201707030001)
Operating System = Windows 7 version 6.1 running on amd64
Java; VM; Vendor = 1.8.0_131
Runtime = Java HotSpot(TM) 64-Bit Server VM 25.131-b11

Reproducibility: Happens sometimes, but not always

STEPS:
  * Ctrl+O
  * paste name of class

ACTUAL:
  class not found

EXPECTED:
  class found

Narrative: 
We use Checkstyle to report problems. Output is something like this:

--- maven-checkstyle-plugin:2.17:check (checkstyle) @ DataPortal ---
There are 3 errors reported by Checkstyle 7.7 with checkstyle-int-config.xml ruleset.
src\main\java\org\inek\dataportal\feature\calculationhospital\EditCalcBasicsDrg.java:[1] (sizes) FileLength: Datei ist 1,371 Zeilen lang (Obergrenze ist 800).
src\main\java\org\inek\dataportal\feature\calculationhospital\EditCalcBasicsPepp.java:[1] (sizes) FileLength: Datei ist 838 Zeilen lang (Obergrenze ist 800).
src\main\java\org\inek\dataportal\feature\certification\CertGrouperResults.java:[1] (sizes) FileLength: Datei ist 899 Zeilen lang (Obergrenze ist 800).

The fastest way to edit one of theses files is to copy its name from Checkstyle's output and to use "goto type" {Ctrl+O}. For some files, this will display an empty list. 
I set the reproducibitilty to "Happens sometimes, but not allways". If a class is not listed, the bug happens always, but not to all classes."Happens on some some files, but not all files"
The bug might depend on the file size

*** Same feature works fine within NetBeans 8.2 ***