Slow (3G) network does not allow to place an order for catalog items with regEx fields.
1. Create a new catalog item or use Access catalog Item.
2. Create a single line text variable with validation RegEx type as number.
3. Launch the SP and try the above created item in slow network (3G).
4. Try to enter the number value in the field and, without moving focus anywhere else, immediately click on Order Now.
Observe, even if the regEx value is valid, it is showing validating text below the Order Now button and not placing any order for the same.
After carefully considering the severity and frequency of the issue, as well as the cost and risk of attempting a fix, a decision has been made not to address this issue in any current or future releases. We do not make this decision lightly and we apologize for any inconvenience.