Not sure which version - uploaded today (Oct 4)
I have been doing the same thing for the last 10 sites I have set up and that is using the HTML tab to insert links into the post - four links in total - two hidden, two clickable.
This worked fine, just a simple copy and paste to save time.
Today with this new version of WP (don't like the new HTML font or bold) I do what I have done previously, and when I have finished in the HTML side I switch back to the Visual to continue and BINGO between the two clickable links no more post! Disappeared.
Thanks Mike FD