Problem adding editors to collections

[nh19]

We are getting reports of editors having problems trying add additional editors to collections. (Possibly an issue with pages timing out.)

[finlaybirnie]

I'm not able to reproduce this on private or public collections - the response time seems fine. Are the affected users all based in a particular area?

[nh19]

There are two collections that different people are trying to add a user to:
International Development - https://talks.ox.ac.uk/user/lists/id/dcd5610b-e863-4d58-a598-a7bdac49a887/
Social Sciences collection - https://talks.ox.ac.uk/user/lists/id/38374238-c829-497d-8c4c-d930cd33bb82/