As discussed many times throughout this forum, the ignore feature is used for a myriad of reasons by members. It would be counter-productive to try to figure out why if you have never had a specific issue with that member.

If a member has you on ignore, they will not receive pm's from you and they cannot post on your threads.

There is no option to tell you who has you on ignore. Hugs and thanks are still seen if the member has you on ignore.

Members have the ability to create their own best experience here. Using the ignore feature is part of that ability. That is a way of doing self care for many members and PC is not only about supporting others, it's about learning to do one's self care as well, and it can be a learning process.