Hello,
I installed a fresh copy of Vm 4.6.0 on a fresh copy of Joomla 5.4, without installing AwoCoupon. I couldn't get coupons to work initially. Entering a coupon just refreshes the page, no errors or messages. The only time I could get a coupon to work is after the user has logged in to joomla front end, then it works. In your cart, are you logged in?
Also I scanned Virtuemart code for that error, and found this line in administrator\components\com_virtuemart\helpers\vrequest.php:525: :
$redirectMsg = 'Invalid Token, in ' . vRequest::getCmd('options') .' view='.vRequest::getCmd('view'). ' task='.vRequest::getCmd('task');
I noticed there is a HOTFIX patch in for 4.6.0:
Which I think seems to replace the vrequest.php file, if I am reading the code correctly. Have you tried that fix also?