Editor inspection not using custom phpcs ruleset

I'm trying to run a custom PHPCS ruleset on a WordPress plugin and a theme. My phpcs is installed locally as a /vendor directory in the root directory for the plugin and theme.

[plugin/theme dir]/vendor/bin contains both phpcs and phpcs.bat (I'm on a Windows machine and prior to getting PhpStorm I have been running phpcs from Git Bash, but PhpStorm is only able to validate the phpcs.bat file, understandably)

I've read through the documentation here: https://www.jetbrains.com/help/phpstorm/2016.3/using-php-code-sniffer-tool.html but admit I find it to be confusing to understand.

My ruleset.xml is located inside the root directory (i.e., the directory where functions.php would reside in a theme), and it's that path I specify in Settings > Editor > Inspections > PHP Code Sniffer validation > Coding standard > Custom Coding Standard

I can verify that my ruleset works, because I can run the following, for example, in Git Bash:

$ ./vendor/bin/phpcs -s --standard=/path/to/ruleset.xml functions.php

That works as expected. But the editor inspection is not picking up this ruleset, and is still flagging parts of my code for sniffs that I excluded in my XML file. Or, if it is using the ruleset but throwing errors, those errors are not getting written to the PhpStorm event log, which seems unlikely but I suppose is possible.

I can't seem to figure out how to resolve this. I've checked JB docs and PEAR, and still not sure what the problem is. Has anybody experienced this issue?