There could be a visual cue (like name initials) when people are inside the ticket checking it. Like for example when we open a proof that shows whomever is in there by displaying the initials on the top right side of the screen
To see presence of others viewing an items like a ticket would be great, we have another system for our IT tickets called FreshService and it offers this and I find it very helpful when considering if I need to pick up a ticket or if someone has it open without needing to ask.