I’d like to share my findings, though it might already be resolved.
This is caused by the preg_replace function inside Insert PHP plugin’s code, which is discussed here in details: http://stackoverflow.com/questions/18993863/preg-replace-causing-dollar-signs-get-removed .
Thus to fix it, you need to manually escape those $ followed by digits, by adding:
$will_bontrager_replacement = preg_replace('/\$(\d)/', '\\\$$1', $will_bontrager_replacement);
above the line :
$will_bontrager_content = preg_replace("/$will_bontrager_search/",$will_bontrager_replacement,$will_bontrager_content,1);
