I have found that if one of the instances (the source or the one you’re looking for) is down it won’t show up when you search on your instance. Someone else said to keep clicking. Growing pains.
It’s a gamble. Now I think I understand why Reddit was always so fucky, they didn’t fix their software. Lemmy has the excuse of not being a huge entity and ran by volunteers on the dev side. I guess Reddit and Lemmy are both ran by volunteers on the social side.