Hi there Marshall!
Sorry to hear about the trouble you’re having with coupons on your site when using mobile.
That is certainly not expected behavior. I just did a test on my site via my smartphone with the latest version of WooCommerce, and the coupon was applied without issues.
What type of mobile device are you testing with? Have you had a chance to try with any other mobile devices?
Often, issues like this are caused by conflicts with code in the theme, or another active plugin on the site. To check for conflicts, please temporarily switch your theme back to Storefront and disable all plugins except for WooCommerce, then check to see if the issue is fixed. If it is, then you can switch your theme back and reactivate plugins one-by-one until you find the one that is causing the issue.
You can read about testing for conflicts in our documentation here:
https://docs.woocommerce.com/document/how-to-test-for-conflicts/
If you are still having trouble with just WooCommerce and Storefront, please share a copy of your site’s System Status. You can find it via WooCommerce > Status. Select “Get system report” and then “Copy for support”. Once you’ve done that, you can paste it here in your reply. Please note that since this is a public forum, you may want to remove any sensitive information that you don’t want shared publicly.
Also, please send a screenshot of the settings for that coupon that is not working. I recommend https://snipboard.io for easily sharing screenshots – please follow the instructions on the page, then paste the URL in your reply here.
Thank you!
