Hi, in the past few days I've had a couple of (pinned) tabs disappear without a trace (leaving a blank spot where they were). Closing and re-opening the browser restores them. Just letting you know.
Same here, but only on one machine (Win 10 64 Bit).
On other computers (Tablet, Win 10 64 Bit, Laptop Win 10 32 Bit, Desktop Win 7 64 Bit) no problems.