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 teamMaren commented
Same issue for me. "Ignore All" not working at all, making checking a long document (300+ pages) very tedious.