Merge with next clip is somewhat broken with 17.10.02 as well. (AFAIK) it works as intended when there is only video track. But when you have (atleast) two video tracks then joining clips on the lower track succeeds (I can seek and play the joined clips) but visually it seems like the rightmost clip was deleted instead, and the program crashes sometimes when trying to interact with that new joined clip. See https://youtu.be/torlQ1pWEfw for visual representation.
Was about to post on this. Still present in 18.06.02, and F5 (refresh) still makes it show up proper. Could have sworn I also saw this happen with video - and another post* also suggested this happened - but could not find repro steps for it.