This issue got fixed in InDesign CC 2019 (v 14.0) released in Oct 2018.
Please update to the latest version of InDesign (v 14.0.1), available via Creative Cloud Desktop app.
We thank you for your support.
Adobe InDesign teamAnonymous commented
InDesign CC - bang up-to-date and I have the same issue 'ignore all' in spell check certainly doesn't ignore all?