Unfortunately, as of now, BDC does not work with IE11. It's not specifically related to 12.3 (nor any previous version). It worked with IE11 GA. Apparently one of recent updates for IE11 must have introduced new security enhancements that prevents BDC from intercepting data properly. The problem has been published as known issue: DNA 12.3 Known Issues#DNA-09. I am afraid it's not a matter of hotfix, so I would not expect it before next release (which is planned this fall). In the meantime, please check SSL decryption for available HTTPS traffic analysis options.