As title said, when sweeping BIP38 with a key that has balance on it, final step yields wrapped C/C++ object of type QComboBox has been deleted without actually sweeping. The decoding is correct so private key can be copied and re-pasted to sweep, but the error persists if you attempt to sweep straight from BIP38.
Eeek! Will fix.
Ok, tested and fixed in latest commit. It was a total oops on my part. Should be 100% fixed now.