Sometimes, the javascript hasn't been loading the cells of the new round and the system continued opening new cells from the old field. This issue has been fixed in the last update.
If this were the described issue, then:
1) it would sometimes appear a win-cell instead of lose-cell, but always only lose-cell instead of win-cell would appear.
2) its appearance would not depend on the amount of the bet, but it depends.
3) its appearance would not depend on the account, but it depends.
So no, not a issue, but programmed behavior, that is a scam.