Hi Nitin,
This is because of the value you're trying to pass into attribute 19, combined with how CoreMetrics delimits attribute values. You're mapping the URL to attribute 19:
https://www.thomaswoodenrailway.com/shop/MattelLoginView?catalogId=15051&langId=-1&storeId=11651&cm_...
But '-_-' is how CM delimits values for attributes, notice this is the value being passed for ALL attributes (note that this is a CM requirement):
HIT-_-Commerce-_-US-_-North America-_-DESKTOP-_-USD-_-US-EN-_-SHOP-_-TW:US:My Account:Login/Register-_-My Account Login/Register-_--_--_--_--_--_--_--_--_-
https://www.thomaswoodenrailway.com/shop/MattelLoginView?catalogId=15051&langId=-1&storeId=11651&cm_...
-_--_-
https://community.tealiumiq.com/questions/129490-_-There was an error with your Username or password combination. Please try again.-_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_--_-
Notice there are a lot of repeated -_- values, it requires them as placeholders for each attribute even if it's blank. When it gets to a19, with your URL that contains several of them, it's assuming the value for 19 is the value for 19-25.
Ultimately, I believe you'll have to change what you map to a19. You could do some JavaScript to replace the delimiter with something else (e.g. -_- replaced with | ), or map the pathname instead (which would exclude all the querystring values). You may also want to consult your CoreMetrics rep to see what the best practice is in this use case. If you need additional help on this use case, please don't hesitate to reach out to your account manager.