Post method issue with google conversion linker from GTM

I’ve recently started using Google Tag Manager (GTM) on my site. In GTM, I ‘ve got the Conversion Linker activated, which, if you come to the site from a Google Ad, will add a a few parameters to the url. The site is using mod_rewrite and htaccess (Enable linking on all page URLs in GTM, conversion linker).

example, example.org/articles/2345/?_ad_source=1&_gl=2342323

The form I have setup is using a post method. But, if GTM adds their parameters to the url, the form stops working.

<form id="form" name="form" method="index.php">
<input type="hidden" name="type" id="type" value="process">
<input type="text" name="test" id="test" value="testing">
<input type="submit" value="submit">
</form>

and I’ve also tried

<form id="form" name="form" method="index.php?type=process">
<input type="text" name="test" id="test" value="testing">
<input type="submit" value="submit">
</form>

if the _gl codes aren’t added as a parameter (Enable linking on all page URLs in GTM), everything is working fine. But with the _gl parameters added, posting the form, the post fields aren’t in the $_post and it seems to be getting the $_get array information instead.

I’m guessing there is something I should be adding to my htaccess to deal with this?

Everything works perfectly with ‘Enable linking on all page URLs’ deactivated in GTM, conversion linker.

I’ve tried testing things with the http-post and http-get arrays, and I’ve tried to catch the post variables earlier on the field.

So I’m not sure what I’d need to change in php or in htaccess, but I’m not quite sure what to look for.