There can be instances where a stock hits a upper/lower circuit and the rebalance order at smallcase does not go through

If any order is pending in a smallcase then you will not able to place other orders without completing or archiving the pending order. 

Archiving a batch excludes those stocks that you have unfilled orders for and completes your smallcase without placing fresh orders. Here is a gif which will guide you in this: Archiving on Web

Once the pending order is archived, you should be able to place other orders in your smallcase. 

For the archived order you will need to look out for when the stock comes off the circuit and then execute that.

For more clarity you can write to support@smallcase.com clearly mentioning your smallcase and userID in the subject.