Unexpected shellcheck parse error for code that runs correctly and looks correct

[xsdg]

For bugs with existing features

• Rule Id (if any, e.g. SC1000): SC1009, SC1072, SC1073
• My shellcheck version (shellcheck --version or "online"): version: 0.11.0
• The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)
• I tried on https://www.shellcheck.net/ and verified that this is still a problem on the latest commit

Here's a snippet or screenshot that shows the problem:

#!/bin/sh
geeqie_exe="$1"
completions_file="$2"

# Make sure input files exist.                                                                                                                                                                
if [ \! \( -x "$geeqie_exe" -a -e "$completions_file" \) ]; then
    echo "Missing input files"
    exit 2
fi

Here's what shellcheck currently says:

In ./build-aux/test-bash-completions.sh line 15:
if [ \! \( -x "$geeqie_exe" -a -e "$completions_file" \) ]; then
^-- SC1009 (info): The mentioned syntax error was in this if expression.
   ^-- SC1073 (error): Couldn't parse this test expression. Fix to allow more checks.
         ^-- SC1072 (error): Expected comparison operator (don't wrap commands in []/[[]]). Fix any mentioned problems and try again.

For more information:
  https://www.shellcheck.net/wiki/SC1072 -- Expected comparison operator (don...
  https://www.shellcheck.net/wiki/SC1073 -- Couldn't parse this test expressi...
  https://www.shellcheck.net/wiki/SC1009 -- The mentioned syntax error was in...

Here's what I wanted or expected to see:

This code runs as expected, and seems to be trivially correct

$(export geeqie_exe="/bin/ls"; export completions_file="/etc/passwd"; [ \! \( -x "$geeqie_exe" -a -e "$completions_file" \) ] && echo failcase || echo bypass)
bypass

$(export geeqie_exe="/bin/noexist"; export completions_file="/etc/passwd"; [ \! \( -x "$geeqie_exe" -a -e "$completions_file" \) ] && echo failcase || echo bypass)
failcase

$(export geeqie_exe="/bin/ls"; export completions_file="/etc/noexist"; [ \! \( -x "$geeqie_exe" -a -e "$completions_file" \) ] && echo failcase || echo bypass)
failcase

$(export geeqie_exe="/bin/noexist"; export completions_file="/etc/noexist"; [ \! \( -x "$geeqie_exe" -a -e "$completions_file" \) ] && echo failcase || echo bypass)
failcase