problem with less than max quantity

I’m selling a grouped product that has the option to buy up to 6 tickets and up to 6 lunches with each order. I’ve set the max quantity per order of 6 for both the tickets and the lunches. I ran a small test run of my sale, since the actual sale will probably sell out in 30 minutes or less, and 2 people experienced a problem where they got the message “You can add up to 6 more tickets to your lunch ticket purchase. You can add up to 6 more tickets to your admission purchase.” and were not able to get to the cart to make their purchases. One person was on Windows / Chrome (latest ver), but were able to complete the same transaction using Windows / Explorer ver 11. The other person was on an iPhone 6s using Safari.

My sale is August 1st, and I have to have it working perfectly by then. Thanks for your help!