Version 3.1.2-4 review problem

We have a problem With one of Our journals after an Upgrade, the editor is not able to make a review, the review Box for the Message does not load, it is visible for a second and looks like it will load but does not, so it is not possible to make a review, other users seem to be able to Access the Message Box. The editor is also the journal manager but is not one of the Authors here, we can not find why he can not proceed With a review.