Why are reply and upvote/downvote buttons missing in this community post?

It's an issue with the forum software at the moment. The powers that be are aware of it. Try logging out and deleting cache/cookies. It has resolved or partially resolved the issue for some people. Also, try another browser.

When I saw your post earlier today I did not have vote icons on my iPhone either. However they are now back. Whether it just needed time for the mods to finish their work, or my clearing my Safari history & Data, I don't know.

If you still do not have the icons try doing Settings > Apps > Safari > Clear History and Website Data.