In Chrome Version 60.0.3112.101 (64-bit) when going to the Koha admin Web UI > Search the Catalog > Search terms and Enter > Click on a title > a MARC preview pop up window appears and blocks access to the page with an endless loading animation that can't be closed. Some other actions also prompt similar pop up window behaviour. The same task in Edge works fine.
I'm guessing this was an upgrade issue related to the browser cache. If anyone finds that this bug still exists please re-open.
This bug was reopened without any new information. If you believe this is a valid bug please re-open and provide information about how to reproduce the bug.