I have seen this in the old UI as well, and I was always about to clear it by clearing the cache on the browser I was using or switching the browser.
Ok, thanks. I will have them try to see if it works. Please see response from Concur Support attached....According to our documentation, the Detach receipt button does not appear because the receipt was added to a mobile quick expense which was imported into an expense report. I am attaching then the article 'Why the detach option is not available on Nextgen UI?' which shows how you can perform a workaround to actually delete this receipt from the expense entry.