Facebook won't let me tag some of my friends.

m not sure if you can help me. I have just created another post. Normally, I have a tag list of up to 50 people, some of whom are my good friends and relatives. Now when I try to tag my good friends and relatives it comes up blank, and yet I can tag a more recent group of folks I confirmed as friends, instead. It's as if Facebook is allowing me to tag only the most recent people, most of whom I would never tag in the first place. Please help me solve this mystery. This makes no sense at all!