system: mac-osx-10.12.6 (sierra)
software: indesign-cs6 ver 8.0
software: indesign-cc(2018) ver 13.0.0

when in gpu-preview mode … center-line 'node' does not appear. when in cpu-preview mode … center-line 'node' does appear. the center-line 'node' has appeared in cs-versions and previous versions … and disappeared in the cc-versions.

i have outlined the steps, and included screen-caps, to reproduce the issue within my post to adobe-forums:
https://forums.adobe.com/thread/2492437

further info about my environment:
Model Name: iMac
Model Identifier: iMac18,3
Processor Name: Intel Core i5
Processor Speed: 3.4 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 16 GB
Boot ROM Version: IM183.0153.B00
SMC Version (system): 2.41f1
Serial Number (system): <<<censored>>>
Hardware UUID: <<<censored>>>