In Firefox, it seems that when using Project Web Application within Office, that when a user is trying to apply a custom filter within Firefox that the Custom Filter is blank. I have attached an image of what this looks like, but I had originally raised this with Microsoft who found this wasn't an issue with the Project Web App service, but with Firefox itself. The verdict that I was given from MS is that 'The difference is the rendering engine of each browser. In this case it seem Firefox does is not able to correctly handle this code.'. After a number of potential resolutions, nothing has worked. We are using the latest firefox version (57.0.4) and have tried with different versions but nothing seems to work. Using private browsing doesn't seem to help the issue either. Currently we can use different browser's as a workaround. Any help would be appreciated. Some more information following investigation: - The issue is that the Project Center custom filters box intermittently hangs when updating the filter and clicking OK. Initial filter was as per the 'Filter fields' screenshot attached. Adding a new line (such as Project Owner container <user's name>, or swapping one of the ORs to an AND) has caused the issue to occur. - Issue has happened on Firefox versions 54, 56.0.2 and the latest version (57.0.4). - Installed plugins are 'OpenH264 Video Codec provided by Cisco Systems, Inc.', 'Widevine Content Decryption Module provided by Google Inc.' and 'Shockwave Flash' (version 27.0 r0). - There were a couple of notifications in the console, however we only opened dev tools after the error had been replicated, so dev tools may still have something to offer. (attached image)