In this case, please help me to logout our app dashboard
Then go to your Shopify Admin Page > Apps > Signin to our app by clicking on the Apps name
This action to avoid the TOKEN going to be missed.
Then, try to push your product to shop again.
If you are still getting this message which about faillure, please help me to check on your pushed products.
Since Shopify has changed their limitation for variants to push to shop. You can click here to check for more information.
If you have reached to 50.000 variants already, then you will be limited by 1000 variants/ per day only.
I hope this might be helpful for you.
Please let us know via chatbox if you need some more help.