I want to be respectful but if they say they don't care what pronouns I use for them, that feels like it puts the decision on me to choose what to call them and I guess I would probably default to "they" because choosing a gender for them feels weird... am I wrong?
As an enby myself, I’d probably default to they/them but try to sprinkle in gendered pronouns when I saw them presenting more one way or another.
Depending on how close your relationship is, you can ask them if they have certain times that they prefer particular pronouns or not.