The thing with Jisun is that none of her friends in the show like Herin, Jenny, Dahee got in the group and she isn't really close to the other members so she might be feeling a little uncomfortable besides that she is a shy person but I'm sure with the time she will feel better and will be more outgoing. I think Jisun is more closer to Seoyeon. All the members are still awkward with each other because they are not a group that have been training for years with each other and even in the show a lot of the girls haven't interact or do mission with the others but with the training,debuting,variety shows,traveling for other countries will make them close. Sorry for my essay