You can encounter a creation error because of the metafield's text type in Shopify. This warning means that StoreAutomator’s default metafield format is a single-line text string, but you sent a multi-line text for the related metafield. Therefore, you need to change the text type of the related metafield to fix this issue.
So, if you see the below warning in some of your SKUs,
Here is what you need to do:
1- Go to your Shopify template, click edit template.
2- Find the mapped metafield in the warning message and click edit.
3- Change the value “:multi_line_text_field” with “:single_line_text_field” from the target field’s name.
4- Click “Save&Close”.
5- Select the products, send force product data update and sync the channel.