There are KNOWN ISSUES that Lightspeed has inside their ecommerce platform. In order to find out what these known issues are, you have to call customer support, report the bug and then ask them if there are any other known issues. This is an ongoing list to help the community stay aware of these known issues. If you have any to add, please reply in a comment and I'll update this post to reflect an ongoing list. Or if @Lightspeed has an update to the issues presented in this post, they can also reply and I'll update this post with their response. Unless of course they would rather just have a Known Issue category that they can use to keep us ALL up-to-date on bugs.
- Multiple users have reported discount codes disappearing in checkout. This is an intermittent issue and may be tied to the next known issue. (updated Aug 7 2019)
- Zip code suffixes intermittently prevent further checkout process or don't calculate taxes. (updated Aug 7 2019)
- Discount codes, in Lightspeed's words; "Simply don't work sometimes". They have figured out that this happens for sure when you leave a checkout page and come back to it, but also happens intermittently for no reason at all. (updated Aug 7 2019)