Hi @philnauta - I tried 6 tests, all worked (see details below)
1 & 2) Chrome (Version 68.0.3440.106) on Mac (normal and incognito) - both scenarios worked
3 & 4) Safari (Version 11.1.2) on Mac (normal and incognito) - both scenarios worked
5 & 6) Safari/iOS 11.3.1) on iPhone 6 (normal and incognito) - both scenarios worked
In the future, you can use an extension like “EditThisCookie” to edit/delete cookies of the current website or you can go here (if you’re on Chrome) and enter the site’s name to delete only that site’s cookies: