The Box API had an issue today, it is listed on their Status Page -> https://status.box.com/
If your Connector is saying that it cannot find the file and you need to wait - this is due to Box's Search API not returning any results.
You can replicate this in Box's UI.
In this picture, you can see I have a file in my Box Account. But if I try to use the SEARCH box above :
Box can't find the file, so the Connector cannot either.
Best course of action is to reach out to Box Support and ask them to re-index / sync your files so they can be found via the Search API.