Make sure you have the following in one of your config files:
# enable Flex Gateway
<IfModule jk_module>
JkMount /*.cfm ajp13
JkMount /*.cfc ajp13
JkMount /*.do ajp13
JkMount /*.jsp ajp13
JkMount /*.cfchart ajp13
JkMount /*.cfres ajp13
JkMount /*.cfm/* ajp13
JkMount /*.cfml/* ajp13
JkMountCopy all
</IfModule>
If you add this to the end of the mod_jk.conf file, just be careful when updating your connector in the future, because it may remove the lines. These commands are required to get the flex2gateway working in CF10. Without these lines, we've seen the exact same behavior you're describing.
Hope this helps!