Unable to encode high-byte order Unicode characters

There seems to be an issue with the Unicode character handling.

I am able to encode ↘ for example which is U+2198 Raw bytes encoded are: 40 7e fb bb fe 28 69 82 00 ec 11 ec 11 ec 11 ec

However a larger Unicode character is U+1F51D

This gets encoded with the following raw bytes: 40 9e fb bb fe da 0b de db 49 d0 ec 11 ec 11 ec

Somehow this is not correct because of a failure to reproduce the Unicode character, although I'm still unsure exactly what the failure is, I suspect it is in QR8BitByte().