Hello @geoffrey, I feel you. Happened some time where I voted, refreshed page, vote gone, voted again, refreshed page, vote gone. Usually at the 3rd time it appears.
Another problem I encounter is with the comments. I write them, press post and they don't appear on the page and it is not saved in drafts. Since then I copy paste the text from a word file and doublecheck it if it has been posted.