Firefox released a new engine called Quantum - https://blog.mozilla.org/blog/2017/11/14/introducing-firefox-quantum/
There are multiple symptoms on multiple platforms of Cognos
New browser design changes how it interacts with webpages
Resolving The Problem
Cognos Business Intelligence and Cognos Analytics only officially supports the Extended Support Release stream https://www.mozilla.org/en-US/firefox/organizations/faq/.
We are aware of the issues introduced with Firefox 57, we are investigating and working on a resolution that will be delivered in a future release. We are already seeing improvements with the nightly builds of Firefox
15 June 2018