Redmine

In Firefox, if I edit an open issue and change the status the page seems to break entirely.
This does not seem to occur in Edge.

The log initially shows nothing of interest (to me!):

I, [2022-05-20T14:42:30.194292 #2375998] INFO -- : [b4ffd2ed-0912-4965-98b1-09637d4341e4] Started PATCH "/redmine/issues/10330/edit.js" for 10.128.17.42 at 2022-05-20 14:42:30 +0100
I, [2022-05-20T14:42:30.195331 #2375998] INFO -- : [b4ffd2ed-0912-4965-98b1-09637d4341e4] Processing by IssuesController#edit as JS
I, [2022-05-20T14:42:30.195542 #2375998] INFO -- : [b4ffd2ed-0912-4965-98b1-09637d4341e4] Parameters: {"utf8"=>"✓", "authenticity_token"=>"Q+m2eSrgAjiZ0ktK8jntWNLndBcVcQ9cjKGSLYkidTTYQnn/mRcaY6QcT4atuCIRV+QW7tgmYLxjtgw+fLRGFA==", "form_update_triggered_by"=>"issue_status_id", "issue"=>{"project_id"=>"4", "tracker_id"=>"11", "subject"=>"Issue subject", "description"=>"Issue description", "status_id"=>"2", "priority_id"=>"2", "assigned_to_id"=>"38", "category_id"=>"15", "parent_issue_id"=>"", "notes"=>"", "private_notes"=>"0", "lock_version"=>"1"}, "was_default_status"=>"1", "time_entry"=>{"hours"=>"", "activity_id"=>"", "comments"=>""}, "last_journal_id"=>"", "next_issue_id"=>"10306", "issue_position"=>"1", "issue_count"=>"9", "id"=>"10330"}
I, [2022-05-20T14:42:30.217537 #2375998] INFO -- : [b4ffd2ed-0912-4965-98b1-09637d4341e4] Current user: ollie.sharratt (id=38)
I, [2022-05-20T14:42:30.277797 #2375998] INFO -- : [b4ffd2ed-0912-4965-98b1-09637d4341e4] Rendered issues/edit.js.erb (Duration: 27.7ms | Allocations: 13482)
I, [2022-05-20T14:42:30.278277 #2375998] INFO -- : [b4ffd2ed-0912-4965-98b1-09637d4341e4] Completed 200 OK in 83ms (Views: 23.8ms | ActiveRecord: 30.5ms | Allocations: 24338)

But if I then update the status again:
I, [2022-05-20T14:45:32.937815 #2375998] INFO -- : [67ff53ed-4bdb-4e13-88d7-b6a8beea8399] Started POST "/redmine/issues/10330/edit.js" for 10.128.17.42 at 2022-05-20 14:45:32 +0100
F, [2022-05-20T14:45:32.939266 #2375998] FATAL -- : [67ff53ed-4bdb-4e13-88d7-b6a8beea8399]
[67ff53ed-4bdb-4e13-88d7-b6a8beea8399] ActionController::RoutingError (No route matches [POST] "/issues/10330/edit.js"):

This has happened on any ticket I attempt to update. Image attached shows the problem in action.