Ideas Pins (previously Story pins) continue to be temperamental. Some of the issues that can come up from time to time:
Board list not appearing/loading
Pins take too long to upload once you try to save the Story/Idea
Tags do not show up or the first tag can be saved and then the tags disappear so you cannot choose more.
I find that this can be frustrating and to avoid wasting time, I usually stop trying and revisit Pinterest after a few hours. Something that seems to work also is switch from Desktop to Mobile - so when I have issues on Desktop I just go on my mobile and try to upload my Idea pin. To speed things up (as it is more tricky to add text on mobile), I prepare my idea pins on CANVA and then just add them on mobile as separate pages.