Last week, I added a snipe (substantially higher than the opening bid) for a bid-only eBay auction that ended with no bids. I used the (production/non-beta) web interface (mobile browser on phone) to set up the snipe, and don't recall seeing any prompt/warning that my eBay account was not linked (link expired). My snipe attempt failed because the link had expired. There were no other bids on the listing, so I'm hopeful that the seller will relist and/or respond to my efforts to contact. I would have found it helpful if the web interface would have blocked/prevented adding a snipe if the eBay account link has expired, or required confirmation (prompt) to add a snipe in this situation.

You did not provide your username or the item number, but the sniper does check your eBay link and sends email when it's about to expire or expired.
Please make sure your email in Profile is the one you normally use and you don't block emails from myibidder.com so you won't miss it next time.