> ...but the company denies it is an issue...
It sounds like the person you spoke with wasn't familiar with the product. They've been aware of the problem for years. It's mentioned in the manual [1] and on their website [2].
[1] http://www.kinesis-ergo.com/wp-content/uploads/2015/06/conto... - Page 28.
[2] http://www.kinesis-ergo.com/support/technical-support/troubl... - "Weird behavior with Advantage keyboard".