problem with using ctrl-x ctrl-e ( open vi editor )

[Hyunho Cho]

Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2
-fdebug-prefix-map=/build/bash-a6qmCk/bash-5.0=.
-fstack-protector-strong -Wformat -Werror=format-security -Wall
-Wno-parentheses -Wno-format-security
uname output: Linux EliteBook 5.4.0-42-generic #46-Ubuntu SMP Fri Jul
10 00:24:02 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.0
Patch Level: 17
Release Status: release

#####################################################

bash$ cat <<\EOF      # without using ctrl-x ctrl-e there is no problem
occurred.
> 111
> 222
> EOF
111
222

---------------------------------------------------------------------------------------

bash$ cat <<\EOF
> 111
>              <---- in this line open vi editor with ctrl-x ctrl-e
                        and add another 222 line then :wq


bash$ cat <<\EOF
> 111
>
cat <<\EOF
111
222
EOF
111            <---- successfully executed cat command with heredoc
222
>
>
>
> ^C           <---- but does not end ">" prompt until enter ctrl-c