Canon has issued a firmware update for the Canon 7D. Firmware version 2.0.5 incorporates the following fix.
1. Fixes a phenomenon in which the image files cannot be transferred using the FTP protocol via USB cable after the EOS 7D camera has established a wireless connection to the Wireless File Transmitter WFT-E5 (A/B/C/D).
You can download the firmware update here on Canon’s website.