MySQL - 1300 - Incorrect utf8 character string when updating

Question

I have a MySQL table column that I am trying to convert from latin1 to UTF8. Some of the values ​​in the column are already UTF8, but they are saved as latin1, which leads to some strange text. Column switching is pretty straight forward, all I have to do is:

ALTER TABLE `user_profiles` MODIFY `last_name` varchar(20) CHARACTER SET utf8; 

The next step is to convert all now double-encoded columns back to UTF8. I can get a list of all these columns by running the following command:

 SELECT `last_name`, CONVERT(CAST(CONVERT(`last_name` USING latin1) AS BINARY) USING utf8) AS `converted_last_name` FROM `user_profiles` WHERE (CONVERT(CAST(CONVERT(`last_name` USING latin1) AS BINARY) USING utf8)) IS NOT NULL AND CONVERT(CAST(CONVERT(`last_name` USING latin1) AS BINARY) USING utf8) != `last_name`; 

Which gives me something like:

 | last_name | converted_last_name | | ----------------|----------------------| | 王维雄 | 王维雄 | | niño de rivera | niño de rivera | | Thölix | Thölix | 

Looks nice. Now that everything is getting weird. If I run the update command:

 UPDATE `user_profiles` SET `last_name` = CONVERT(CAST(CONVERT(`last_name` USING latin1) AS BINARY) USING utf8) WHERE (CONVERT(CAST(CONVERT(`last_name` USING latin1) AS BINARY) USING utf8)) IS NOT NULL AND CONVERT(CAST(CONVERT(`last_name` USING latin1) AS BINARY) USING utf8) != `last_name` 

I get error 1300 as follows:

 #1300 - Invalid utf8 character string: 'E36F' 

Any idea why the update is different from the selected one? Any thoughts on how to get around this?